--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -123,16 +123,17 @@
 #include "nsThreadManager.h"
 #include "nsAnonymousTemporaryFile.h"
 #include "nsISpellChecker.h"
 #include "nsClipboardProxy.h"
 #include "nsDirectoryService.h"
 #include "nsDirectoryServiceUtils.h"
 #include "nsDirectoryServiceDefs.h"
 #include "nsContentPermissionHelper.h"
+#include "nsPluginHost.h"
 #ifdef NS_PRINTING
 #include "nsPrintingProxy.h"
 #endif
 
 #include "IHistory.h"
 #include "nsNetUtil.h"
 
 #include "base/message_loop.h"
@@ -3369,10 +3370,20 @@ ContentChild::RecvRefreshScreens(nsTArra
 }
 
 already_AddRefed<nsIEventTarget>
 ContentChild::GetEventTargetFor(TabChild* aTabChild)
 {
   return IToplevelProtocol::GetActorEventTarget(aTabChild);
 }
 
+mozilla::ipc::IPCResult
+ContentChild::RecvSetPluginList(const uint32_t& aPluginEpoch,
+                                nsTArray<plugins::PluginTag>&& aPluginTags,
+                                nsTArray<plugins::FakePluginTag>&& aFakePluginTags)
+{
+  RefPtr<nsPluginHost> host = nsPluginHost::GetInst();
+  host->SetPluginsInContent(aPluginEpoch, aPluginTags, aFakePluginTags);
+  return IPC_OK();
+}
+
 } // namespace dom
 } // namespace mozilla

--- a/dom/ipc/ContentChild.h
+++ b/dom/ipc/ContentChild.h
@@ -656,16 +656,19 @@ public:
                       const Optional<int64_t>& aLastModified,
                       bool aExistenceCheck, bool aIsFromNsIFile);
 
   typedef std::function<void(PRFileDesc*)> AnonymousTemporaryFileCallback;
   nsresult AsyncOpenAnonymousTemporaryFile(const AnonymousTemporaryFileCallback& aCallback);
 
   virtual already_AddRefed<nsIEventTarget> GetEventTargetFor(TabChild* aTabChild) override;
 
+  mozilla::ipc::IPCResult
+  RecvSetPluginList(const uint32_t& aPluginEpoch, nsTArray<PluginTag>&& aPluginTags, nsTArray<FakePluginTag>&& aFakePluginTags) override;
+
 private:
   static void ForceKillTimerCallback(nsITimer* aTimer, void* aClosure);
   void StartForceKillTimer();
 
   virtual void ActorDestroy(ActorDestroyReason why) override;
 
   virtual void ProcessingError(Result aCode, const char* aReason) override;
 

--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -1157,27 +1157,16 @@ ContentParent::RecvGetBlocklistState(con
   }
 
   if (NS_FAILED(tag->GetBlocklistState(aState))) {
     return IPC_FAIL_NO_REASON(this);
   }
   return IPC_OK();
 }
 
-mozilla::ipc::IPCResult
-ContentParent::RecvFindPlugins(const uint32_t& aPluginEpoch,
-                               nsresult* aRv,
-                               nsTArray<PluginTag>* aPlugins,
-                               nsTArray<FakePluginTag>* aFakePlugins,
-                               uint32_t* aNewPluginEpoch)
-{
-  *aRv = mozilla::plugins::FindPluginsForContent(aPluginEpoch, aPlugins, aFakePlugins, aNewPluginEpoch);
-  return IPC_OK();
-}
-
 /*static*/ TabParent*
 ContentParent::CreateBrowser(const TabContext& aContext,
                              Element* aFrameElement,
                              ContentParent* aOpenerContentParent,
                              TabParent* aSameTabGroupAs,
                              uint64_t aNextTabParentId)
 {
   PROFILER_LABEL_FUNC(js::ProfileEntry::Category::OTHER);
@@ -2443,16 +2432,21 @@ ContentParent::InitInternal(ProcessPrior
 
   {
     nsTArray<BlobURLRegistrationData> registrations;
     if (nsHostObjectProtocolHandler::GetAllBlobURLEntries(registrations,
                                                           this)) {
       Unused << SendInitBlobURLs(registrations);
     }
   }
+
+  // Start up nsPluginHost and run FindPlugins to cache the plugin list.
+  // If this isn't our first content process, just send over cached list.
+  RefPtr<nsPluginHost> pluginHost = nsPluginHost::GetInst();
+  pluginHost->SendPluginsToContent();
 }
 
 bool
 ContentParent::IsAlive() const
 {
   return mIsAlive;
 }
 
@@ -5292,8 +5286,16 @@ ContentParent::CanCommunicateWith(Conten
   if (!cpm->GetParentProcessId(ChildID(), &parentId)) {
     return false;
   }
   if (IsForJSPlugin()) {
     return parentId == ContentParentId(0);
   }
   return parentId == aOtherProcess;
 }
+
+mozilla::ipc::IPCResult
+ContentParent::RecvMaybeReloadPlugins()
+{
+  RefPtr<nsPluginHost> pluginHost = nsPluginHost::GetInst();
+  pluginHost->ReloadPlugins();
+  return IPC_OK();
+}

--- a/dom/ipc/ContentParent.h
+++ b/dom/ipc/ContentParent.h
@@ -293,29 +293,25 @@ public:
                                                            Endpoint<PContentBridgeParent>* aEndpoint) override;
 
   virtual mozilla::ipc::IPCResult RecvCreateGMPService() override;
 
   virtual mozilla::ipc::IPCResult RecvLoadPlugin(const uint32_t& aPluginId, nsresult* aRv,
                                                  uint32_t* aRunID,
                                                  Endpoint<PPluginModuleParent>* aEndpoint) override;
 
+  virtual mozilla::ipc::IPCResult RecvMaybeReloadPlugins() override;
+
   virtual mozilla::ipc::IPCResult RecvConnectPluginBridge(const uint32_t& aPluginId,
                                                           nsresult* aRv,
                                                           Endpoint<PPluginModuleParent>* aEndpoint) override;
 
   virtual mozilla::ipc::IPCResult RecvGetBlocklistState(const uint32_t& aPluginId,
                                                         uint32_t* aIsBlocklisted) override;
 
-  virtual mozilla::ipc::IPCResult RecvFindPlugins(const uint32_t& aPluginEpoch,
-                                                  nsresult* aRv,
-                                                  nsTArray<PluginTag>* aPlugins,
-                                                  nsTArray<FakePluginTag>* aFakePlugins,
-                                                  uint32_t* aNewPluginEpoch) override;
-
   virtual mozilla::ipc::IPCResult RecvUngrabPointer(const uint32_t& aTime) override;
 
   virtual mozilla::ipc::IPCResult RecvRemovePermission(const IPC::Principal& aPrincipal,
                                                        const nsCString& aPermissionType,
                                                        nsresult* aRv) override;
 
   NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(ContentParent, nsIObserver)
 

--- a/dom/ipc/PContent.ipdl
+++ b/dom/ipc/PContent.ipdl
@@ -606,16 +606,27 @@ child:
     async ProvideAnonymousTemporaryFile(uint64_t aID, FileDescOrError aFD);
 
     async SetPermissionsWithKey(nsCString aPermissionKey, Permission[] aPermissions);
 
     async RefreshScreens(ScreenDetails[] aScreens);
 
     async PIPCBlobInputStream(nsID aID, uint64_t aSize);
 
+    /**
+     * This call takes the set of plugins loaded in the chrome process, and
+     * sends them to the content process. However, in many cases this set will
+     * not have changed since the last SetPluginList message. To keep track of
+     * this, the chrome process increments an epoch number every time the set of
+     * plugins changes. The chrome process sends up the last epoch it observed.
+     * If the epoch last seen by the content process is the same, the content
+     * process ignores the update. Otherwise the content process updates its
+     * list and reloads its plugins.
+     **/
+    async SetPluginList(uint32_t pluginEpoch, PluginTag[] plugins, FakePluginTag[] fakePlugins);
 parent:
     async InitBackground(Endpoint<PBackgroundParent> aEndpoint);
 
     sync CreateChildProcess(IPCTabContext context,
                             ProcessPriority priority,
                             TabId openerTabId,
                             TabId tabId)
         returns (ContentParentId cpId, bool isForBrowser);
@@ -641,30 +652,16 @@ parent:
     sync ConnectPluginBridge(uint32_t aPluginId)
         returns (nsresult rv, Endpoint<PPluginModuleParent> aEndpoint);
 
     /**
      * Return the current blocklist state for a particular plugin.
      */
     sync GetBlocklistState(uint32_t aPluginId) returns (uint32_t aState);
 
-    /**
-     * This call returns the set of plugins loaded in the chrome
-     * process. However, in many cases this set will not have changed since the
-     * last FindPlugins message. Consequently, the chrome process increments an
-     * epoch number every time the set of plugins changes. The content process
-     * sends up the last epoch it observed. If the epochs are the same, the
-     * chrome process returns no plugins. Otherwise it returns a complete list.
-     *
-     * |pluginEpoch| is the epoch last observed by the content
-     * process. |newPluginEpoch| is the current epoch in the chrome process. If
-     * |pluginEpoch == newPluginEpoch|, then |plugins| will be left empty.
-     */
-    sync FindPlugins(uint32_t pluginEpoch) returns (nsresult aResult, PluginTag[] plugins, FakePluginTag[] fakePlugins, uint32_t newPluginEpoch);
-
     async PJavaScript();
 
     async PRemoteSpellcheckEngine();
 
     async InitCrashReporter(Shmem shmem, NativeThreadId tid);
 
     /**
      * Is this token compatible with the provided version?
@@ -1089,16 +1086,17 @@ parent:
 
     sync GetA11yContentId() returns (uint32_t aContentId);
     async A11yHandlerControl(uint32_t aPid,
                              IHandlerControlHolder aHandlerControl);
 
     async AddMemoryReport(MemoryReport aReport);
     async FinishMemoryReport(uint32_t aGeneration);
 
+    async MaybeReloadPlugins();
 both:
      async AsyncMessage(nsString aMessage, CpowEntry[] aCpows,
                         Principal aPrincipal, ClonedMessageData aData);
 
     /**
      * Notify `push-subscription-modified` observers in the parent and child.
      */
     async NotifyPushSubscriptionModifiedObservers(nsCString scope,

--- a/dom/plugins/base/nsPluginHost.cpp
+++ b/dom/plugins/base/nsPluginHost.cpp
@@ -46,16 +46,17 @@
 #include "nsIScriptChannel.h"
 #include "nsIBlocklistService.h"
 #include "nsVersionComparator.h"
 #include "nsIObjectLoadingContent.h"
 #include "nsIWritablePropertyBag2.h"
 #include "nsICategoryManager.h"
 #include "nsPluginStreamListenerPeer.h"
 #include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/ContentParent.h"
 #include "mozilla/dom/FakePluginTagInitBinding.h"
 #include "mozilla/LoadInfo.h"
 #include "mozilla/plugins/PluginAsyncSurrogate.h"
 #include "mozilla/plugins/PluginBridge.h"
 #include "mozilla/plugins/PluginTypes.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/ipc/URIUtils.h"
 
@@ -262,24 +263,16 @@ static bool UnloadPluginsASAP()
 }
 
 nsPluginHost::nsPluginHost()
   : mPluginsLoaded(false)
   , mOverrideInternalTypes(false)
   , mPluginsDisabled(false)
   , mPluginEpoch(0)
 {
-  // Bump the pluginchanged epoch on startup. This insures content gets a
-  // good plugin list the first time it requests it. Normally we'd just
-  // init this to 1, but due to the unique nature of our ctor we need to do
-  // this manually.
-  if (XRE_IsParentProcess()) {
-    IncrementChromeEpoch();
-  }
-
   // check to see if pref is set at startup to let plugins take over in
   // full page mode for certain image mime types that we handle internally
   mOverrideInternalTypes =
     Preferences::GetBool("plugin.override_internal_types", false);
 
   mPluginsDisabled = Preferences::GetBool("plugin.disable", false);
 
   Preferences::AddStrongObserver(this, "plugin.disable");
@@ -298,16 +291,23 @@ nsPluginHost::nsPluginHost()
 #ifdef PLUGIN_LOGGING
   MOZ_LOG(nsPluginLogging::gNPNLog, PLUGIN_LOG_ALWAYS,("NPN Logging Active!\n"));
   MOZ_LOG(nsPluginLogging::gPluginLog, PLUGIN_LOG_ALWAYS,("General Plugin Logging Active! (nsPluginHost::ctor)\n"));
   MOZ_LOG(nsPluginLogging::gNPPLog, PLUGIN_LOG_ALWAYS,("NPP Logging Active!\n"));
 
   PLUGIN_LOG(PLUGIN_LOG_ALWAYS,("nsPluginHost::ctor\n"));
   PR_LogFlush();
 #endif
+
+  // Load plugins on creation, as there's a good chance we'll need to send them
+  // to content processes directly after creation.
+  if (XRE_IsParentProcess())
+  {
+    LoadPlugins();
+  }
 }
 
 nsPluginHost::~nsPluginHost()
 {
   PLUGIN_LOG(PLUGIN_LOG_ALWAYS,("nsPluginHost::dtor\n"));
 
   UnloadPlugins();
   sInst = nullptr;
@@ -355,18 +355,30 @@ bool nsPluginHost::IsRunningPlugin(nsPlu
   return false;
 }
 
 nsresult nsPluginHost::ReloadPlugins()
 {
   PLUGIN_LOG(PLUGIN_LOG_NORMAL,
   ("nsPluginHost::ReloadPlugins Begin\n"));
 
-  nsresult rv = NS_OK;
-
+  // If we're calling this from a content process, forward the reload request to
+  // the parent process. If plugins actually changed, it will notify us
+  // asynchronously later.
+  if (XRE_IsContentProcess())
+  {
+    Unused << mozilla::dom::ContentChild::GetSingleton()->SendMaybeReloadPlugins();
+    // In content processes, always signal that plugins have not changed. We
+    // will never know if they changed here unless we make slow synchronous
+    // calls. This information will hopefully only be wrong once, as if there
+    // has been a plugin update, we expect to have gotten notification from the
+    // parent process and everything should be updated by the next time this is
+    // called. See Bug 1337058 for more info.
+    return NS_ERROR_PLUGINS_PLUGINSNOTCHANGED;
+  }
   // this will create the initial plugin list out of cache
   // if it was not created yet
   if (!mPluginsLoaded)
     return LoadPlugins();
 
   // we are re-scanning plugins. New plugins may have been added, also some
   // plugins may have been removed, so we should probably shut everything down
   // but don't touch running (active and not stopped) plugins
@@ -377,16 +389,24 @@ nsresult nsPluginHost::ReloadPlugins()
   // look for possible changes
   bool pluginschanged = true;
   FindPlugins(false, &pluginschanged);
 
   // if no changed detected, return an appropriate error code
   if (!pluginschanged)
     return NS_ERROR_PLUGINS_PLUGINSNOTCHANGED;
 
+  return ActuallyReloadPlugins();
+}
+
+nsresult
+nsPluginHost::ActuallyReloadPlugins()
+{
+  nsresult rv = NS_OK;
+
   // shutdown plugins and kill the list if there are no running plugins
   RefPtr<nsPluginTag> prev;
   RefPtr<nsPluginTag> next;
 
   for (RefPtr<nsPluginTag> p = mPlugins; p != nullptr;) {
     next = p->mNext;
 
     // only remove our plugin from the list if it's not running.
@@ -410,16 +430,23 @@ nsresult nsPluginHost::ReloadPlugins()
   }
 
   // set flags
   mPluginsLoaded = false;
 
   // load them again
   rv = LoadPlugins();
 
+  if (XRE_IsParentProcess())
+  {
+    // If the plugin list changed, update content. If the plugin list changed
+    // for the content process, it will also reload plugins.
+    SendPluginsToContent();
+  }
+
   PLUGIN_LOG(PLUGIN_LOG_NORMAL,
   ("nsPluginHost::ReloadPlugins End\n"));
 
   return rv;
 }
 
 #define NS_RETURN_UASTRING_SIZE 128
 
@@ -2271,21 +2298,21 @@ WatchRegKey(uint32_t aRoot, nsCOMPtr<nsI
     return;
   }
   aKey->StartWatching(true);
 }
 #endif
 
 nsresult nsPluginHost::LoadPlugins()
 {
-#ifdef ANDROID
+  // This should only be run in the parent process. On plugin list change, we'll
+  // update observers in the content process as part of SetPluginsInContent
   if (XRE_IsContentProcess()) {
     return NS_OK;
   }
-#endif
   // do not do anything if it is already done
   // use ReloadPlugins() to enforce loading
   if (mPluginsLoaded)
     return NS_OK;
 
   if (mPluginsDisabled)
     return NS_OK;
 
@@ -2310,42 +2337,34 @@ nsresult nsPluginHost::LoadPlugins()
     if (obsService)
       obsService->NotifyObservers(nullptr, "plugins-list-updated", nullptr);
   }
 
   return NS_OK;
 }
 
 nsresult
-nsPluginHost::FindPluginsInContent(bool aCreatePluginList, bool* aPluginsChanged)
+nsPluginHost::SetPluginsInContent(uint32_t aPluginEpoch,
+                                  nsTArray<mozilla::plugins::PluginTag>& aPlugins,
+                                  nsTArray<mozilla::plugins::FakePluginTag>& aFakePlugins)
 {
   MOZ_ASSERT(XRE_IsContentProcess());
 
-  dom::ContentChild* cp = dom::ContentChild::GetSingleton();
-  nsresult rv;
   nsTArray<PluginTag> plugins;
+
   nsTArray<FakePluginTag> fakePlugins;
-  uint32_t parentEpoch;
-  if (!cp->SendFindPlugins(ChromeEpochForContent(), &rv, &plugins, &fakePlugins, &parentEpoch) ||
-      NS_FAILED(rv)) {
-    return NS_ERROR_NOT_AVAILABLE;
-  }
-
-  if (parentEpoch != ChromeEpochForContent()) {
-    *aPluginsChanged = true;
-    if (!aCreatePluginList) {
-      return NS_OK;
-    }
-
-    // Don't do this if aCreatePluginList is false. Otherwise, when we actually
-    // want to create the list, we'll come back here and do nothing.
-    SetChromeEpochForContent(parentEpoch);
-
-    for (size_t i = 0; i < plugins.Length(); i++) {
-      PluginTag& tag = plugins[i];
+
+  if (aPluginEpoch != ChromeEpochForContent()) {
+    // Since we know we're going to be repopulating the lists anyways, trigger a
+    // reload now to clear out all old entries.
+    ActuallyReloadPlugins();
+
+    SetChromeEpochForContent(aPluginEpoch);
+
+    for (auto tag : aPlugins) {
 
       // Don't add the same plugin again.
       if (nsPluginTag* existing = PluginWithId(tag.id())) {
         UpdateInMemoryPluginInfo(existing);
         continue;
       }
 
       nsPluginTag *pluginTag = new nsPluginTag(tag.id(),
@@ -2362,17 +2381,17 @@ nsPluginHost::FindPluginsInContent(bool 
                                                tag.supportsAsyncInit(),
                                                tag.supportsAsyncRender(),
                                                tag.lastModifiedTime(),
                                                tag.isFromExtension(),
                                                tag.sandboxLevel());
       AddPluginTag(pluginTag);
     }
 
-    for (const auto& tag : fakePlugins) {
+    for (const auto& tag : aFakePlugins) {
       // Don't add the same plugin again.
       for (const auto& existingTag : mFakePlugins) {
         if (existingTag->Id() == tag.id()) {
           continue;
         }
       }
 
       RefPtr<nsFakePluginTag> pluginTag =
@@ -2389,16 +2408,22 @@ nsPluginHost::FindPluginsInContent(bool 
         Preferences::GetCString(kPrefDisableFullPage);
       for (uint32_t i = 0; i < pluginTag->MimeTypes().Length(); i++) {
         if (!IsTypeInList(pluginTag->MimeTypes()[i], disableFullPage)) {
           RegisterWithCategoryManager(pluginTag->MimeTypes()[i],
                                       ePluginRegister);
         }
       }
     }
+
+    nsCOMPtr<nsIObserverService> obsService =
+      mozilla::services::GetObserverService();
+    if (obsService) {
+      obsService->NotifyObservers(nullptr, "plugins-list-updated", nullptr);
+    }
   }
 
   mPluginsLoaded = true;
   return NS_OK;
 }
 
 // if aCreatePluginList is false we will just scan for plugins
 // and see if any changes have been made to the plugins.
@@ -2406,18 +2431,20 @@ nsPluginHost::FindPluginsInContent(bool 
 nsresult nsPluginHost::FindPlugins(bool aCreatePluginList, bool * aPluginsChanged)
 {
   Telemetry::AutoTimer<Telemetry::FIND_PLUGINS> telemetry;
 
   NS_ENSURE_ARG_POINTER(aPluginsChanged);
 
   *aPluginsChanged = false;
 
+  // If plugins are found or change, the content process will be notified by the
+  // parent process. Bail out early if this is called from the content process.
   if (XRE_IsContentProcess()) {
-    return FindPluginsInContent(aCreatePluginList, aPluginsChanged);
+    return NS_OK;
   }
 
   nsresult rv;
 
   // Read cached plugins info. If the profile isn't yet available then don't
   // scan for plugins
   if (ReadPluginInfo() == NS_ERROR_NOT_AVAILABLE)
     return NS_OK;
@@ -2536,90 +2563,80 @@ nsresult nsPluginHost::FindPlugins(bool 
   // No more need for cached plugins. Clear it up.
   NS_ITERATIVE_UNREF_LIST(RefPtr<nsPluginTag>, mCachedPlugins, mNext);
   NS_ITERATIVE_UNREF_LIST(RefPtr<nsInvalidPluginTag>, mInvalidPlugins, mNext);
 
   return NS_OK;
 }
 
 nsresult
-mozilla::plugins::FindPluginsForContent(uint32_t aPluginEpoch,
-                                        nsTArray<PluginTag>* aPlugins,
-                                        nsTArray<FakePluginTag>* aFakePlugins,
-                                        uint32_t* aNewPluginEpoch)
+nsPluginHost::SendPluginsToContent()
 {
   MOZ_ASSERT(XRE_IsParentProcess());
 
-  RefPtr<nsPluginHost> host = nsPluginHost::GetInst();
-  return host->FindPluginsForContent(aPluginEpoch, aPlugins, aFakePlugins, aNewPluginEpoch);
-}
-
-nsresult
-nsPluginHost::FindPluginsForContent(uint32_t aPluginEpoch,
-                                    nsTArray<PluginTag>* aPlugins,
-                                    nsTArray<FakePluginTag>* aFakePlugins,
-                                    uint32_t* aNewPluginEpoch)
-{
-  MOZ_ASSERT(XRE_IsParentProcess());
-
+  nsTArray<PluginTag> pluginTags;
+  nsTArray<FakePluginTag> fakePluginTags;
   // Load plugins so that the epoch is correct.
   nsresult rv = LoadPlugins();
   if (NS_FAILED(rv)) {
     return rv;
   }
 
-  *aNewPluginEpoch = ChromeEpoch();
-  if (aPluginEpoch == ChromeEpoch()) {
-    return NS_OK;
-  }
+  uint32_t newPluginEpoch = ChromeEpoch();
 
   nsTArray<nsCOMPtr<nsIInternalPluginTag>> plugins;
   GetPlugins(plugins, true);
 
   for (size_t i = 0; i < plugins.Length(); i++) {
     nsCOMPtr<nsIInternalPluginTag> basetag = plugins[i];
 
     nsCOMPtr<nsIFakePluginTag> faketag = do_QueryInterface(basetag);
     if (faketag) {
       /// FIXME-jsplugins - We need to add a nsIInternalPluginTag->AsNative() to
       /// avoid this hacky static cast
       nsFakePluginTag* tag = static_cast<nsFakePluginTag*>(basetag.get());
       mozilla::ipc::URIParams handlerURI;
       SerializeURI(tag->HandlerURI(), handlerURI);
-      aFakePlugins->AppendElement(FakePluginTag(tag->Id(),
-                                                handlerURI,
-                                                tag->Name(),
-                                                tag->Description(),
-                                                tag->MimeTypes(),
-                                                tag->MimeDescriptions(),
-                                                tag->Extensions(),
-                                                tag->GetNiceFileName(),
-                                                tag->SandboxScript()));
+      fakePluginTags.AppendElement(FakePluginTag(tag->Id(),
+                                                 handlerURI,
+                                                 tag->Name(),
+                                                 tag->Description(),
+                                                 tag->MimeTypes(),
+                                                 tag->MimeDescriptions(),
+                                                 tag->Extensions(),
+                                                 tag->GetNiceFileName(),
+                                                 tag->SandboxScript()));
       continue;
     }
 
     /// FIXME-jsplugins - We need to cleanup the various plugintag classes
     /// to be more sane and avoid this dance
     nsPluginTag *tag = static_cast<nsPluginTag *>(basetag.get());
 
-    aPlugins->AppendElement(PluginTag(tag->mId,
-                                      tag->Name(),
-                                      tag->Description(),
-                                      tag->MimeTypes(),
-                                      tag->MimeDescriptions(),
-                                      tag->Extensions(),
-                                      tag->mIsJavaPlugin,
-                                      tag->mIsFlashPlugin,
-                                      tag->mSupportsAsyncInit,
-                                      tag->mSupportsAsyncRender,
-                                      tag->FileName(),
-                                      tag->Version(),
-                                      tag->mLastModifiedTime,
-                                      tag->IsFromExtension(),
-                                      tag->mSandboxLevel));
+    pluginTags.AppendElement(PluginTag(tag->mId,
+                                       tag->Name(),
+                                       tag->Description(),
+                                       tag->MimeTypes(),
+                                       tag->MimeDescriptions(),
+                                       tag->Extensions(),
+                                       tag->mIsJavaPlugin,
+                                       tag->mIsFlashPlugin,
+                                       tag->mSupportsAsyncInit,
+                                       tag->mSupportsAsyncRender,
+                                       tag->FileName(),
+                                       tag->Version(),
+                                       tag->mLastModifiedTime,
+                                       tag->IsFromExtension(),
+                                       tag->mSandboxLevel));
+  }
+  nsTArray<dom::ContentParent*> parents;
+  dom::ContentParent::GetAll(parents);
+  for (auto p : parents)
+  {
+    Unused << p->SendSetPluginList(newPluginEpoch, pluginTags, fakePluginTags);
   }
   return NS_OK;
 }
 
 void
 nsPluginHost::UpdateInMemoryPluginInfo(nsPluginTag* aPluginTag)
 {
   NS_ITERATIVE_UNREF_LIST(RefPtr<nsPluginTag>, mCachedPlugins, mNext);

--- a/dom/plugins/base/nsPluginHost.h
+++ b/dom/plugins/base/nsPluginHost.h
@@ -247,16 +247,20 @@ public:
 
   void CreateWidget(nsPluginInstanceOwner* aOwner);
 
   nsresult EnumerateSiteData(const nsACString& domain,
                              const InfallibleTArray<nsCString>& sites,
                              InfallibleTArray<nsCString>& result,
                              bool firstMatchOnly);
 
+  nsresult SendPluginsToContent();
+  nsresult SetPluginsInContent(uint32_t aPluginEpoch,
+                               nsTArray<mozilla::plugins::PluginTag>& aPlugins,
+                               nsTArray<mozilla::plugins::FakePluginTag>& aFakePlugins);
 private:
   friend class nsPluginUnloadRunnable;
 
   void DestroyRunningInstances(nsPluginTag* aPluginTag);
 
   // Writes updated plugins settings to disk and unloads the plugin
   // if it is now disabled. Should only be called by the plugin tag in question
   void UpdatePluginInfo(nsPluginTag* aPluginTag);
@@ -296,18 +300,16 @@ private:
   // be filled in with the MIME type the plugin is registered for.
   nsPluginTag* FindNativePluginForExtension(const nsACString & aExtension,
                                             /* out */ nsACString & aMimeType,
                                             bool aCheckEnabled);
 
   nsresult
   FindStoppedPluginForURL(nsIURI* aURL, nsIPluginInstanceOwner *aOwner);
 
-  nsresult FindPluginsInContent(bool aCreatePluginList, bool * aPluginsChanged);
-
   nsresult
   FindPlugins(bool aCreatePluginList, bool * aPluginsChanged);
 
   // FIXME revisit, no ns prefix
   // Registers or unregisters the given mime type with the category manager
   enum nsRegisterType { ePluginRegister,
                         ePluginUnregister,
                         // Checks if this type should still be registered first
@@ -363,16 +365,18 @@ private:
 
   // To be used by the content process to get/set the last observed epoch value
   // from the chrome process.
   uint32_t ChromeEpochForContent();
   void SetChromeEpochForContent(uint32_t aEpoch);
 
   void UpdateInMemoryPluginInfo(nsPluginTag* aPluginTag);
 
+  nsresult ActuallyReloadPlugins();
+
   RefPtr<nsPluginTag> mPlugins;
   RefPtr<nsPluginTag> mCachedPlugins;
   RefPtr<nsInvalidPluginTag> mInvalidPlugins;
 
   nsTArray< RefPtr<nsFakePluginTag> > mFakePlugins;
 
   bool mPluginsLoaded;
 

--- a/ipc/ipdl/sync-messages.ini
+++ b/ipc/ipdl/sync-messages.ini
@@ -860,18 +860,16 @@ description =
 [PContent::BridgeToChildProcess]
 description =
 [PContent::LoadPlugin]
 description =
 [PContent::ConnectPluginBridge]
 description =
 [PContent::GetBlocklistState]
 description =
-[PContent::FindPlugins]
-description =
 [PContent::NSSU2FTokenIsCompatibleVersion]
 description =
 [PContent::NSSU2FTokenIsRegistered]
 description =
 [PContent::NSSU2FTokenRegister]
 description =
 [PContent::NSSU2FTokenSign]
 description =