--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -264,16 +264,19 @@ using namespace mozilla::system;
 #endif
 
 #ifdef XP_WIN
 #include "mozilla/widget/AudioSession.h"
 #endif
 
 #include "VRManagerParent.h"            // for VRManagerParent
 
+// For VP9Benchmark::sBenchmarkFpsPref
+#include "Benchmark.h"
+
 static NS_DEFINE_CID(kCClipboardCID, NS_CLIPBOARD_CID);
 
 #if defined(XP_WIN)
 // e10s forced enable pref, defined in nsAppRunner.cpp
 extern const char* kForceEnableE10sPref;
 #endif
 
 using base::ChildPrivileges;
@@ -5706,16 +5709,27 @@ ContentParent::RecvGetAndroidSystemInfo(
   nsSystemInfo::GetAndroidSystemInfo(aInfo);
   return true;
 #else
   MOZ_CRASH("wrong platform!");
   return false;
 #endif
 }
 
+bool
+ContentParent::RecvNotifyBenchmarkResult(const nsString& aCodecName,
+                                         const uint32_t& aDecodeFPS)
+
+{
+  if (aCodecName.EqualsLiteral("VP9")) {
+    Preferences::SetUint(VP9Benchmark::sBenchmarkFpsPref, aDecodeFPS);
+  }
+  return true;
+}
+
 void
 ContentParent::StartProfiler(nsIProfilerStartParams* aParams)
 {
 #ifdef MOZ_ENABLE_PROFILER_SPS
   if (NS_WARN_IF(!aParams)) {
     return;
   }
 

--- a/dom/ipc/ContentParent.h
+++ b/dom/ipc/ContentParent.h
@@ -1087,16 +1087,19 @@ private:
 
   virtual bool RecvGetDeviceStorageLocation(const nsString& aType,
                                             nsString* aPath) override;
 
   virtual bool RecvGetDeviceStorageLocations(DeviceStorageLocationInfo* info) override;
 
   virtual bool RecvGetAndroidSystemInfo(AndroidSystemInfo* aInfo) override;
 
+  virtual bool RecvNotifyBenchmarkResult(const nsString& aCodecName,
+                                         const uint32_t& aDecodeFPS) override;
+
   // If you add strong pointers to cycle collected objects here, be sure to
   // release these objects in ShutDownProcess.  See the comment there for more
   // details.
 
   GeckoChildProcessHost* mSubprocess;
   ContentParent* mOpener;
 
   ContentParentId mChildID;

--- a/dom/ipc/PContent.ipdl
+++ b/dom/ipc/PContent.ipdl
@@ -1192,15 +1192,22 @@ parent:
      * Tells the parent to ungrab the pointer on the default display.
      *
      * This is for GTK platforms where we have to ensure the pointer ungrab happens in the
      * chrome process as that's the process that receives the pointer event.
      */
     sync UngrabPointer(uint32_t time);
 
     sync RemovePermission(Principal principal, nsCString permissionType) returns (nsresult rv);
+
+    /**
+     * Tell the parent that a decoder's' benchmark has been completed.
+     * The result can then be stored in permanent storage.
+     */
+    async NotifyBenchmarkResult(nsString aCodecName, uint32_t aDecodeFPS);
+
 both:
      async AsyncMessage(nsString aMessage, ClonedMessageData aData,
                         CpowEntry[] aCpows, Principal aPrincipal);
 };
 
 }
 }