--- a/dom/ipc/TabChild.cpp
+++ b/dom/ipc/TabChild.cpp
@@ -2660,16 +2660,26 @@ TabChild::MakeHidden()
   }
 
   CompositorBridgeChild* compositor = CompositorBridgeChild::Get();
 
   // Clear cached resources directly. This avoids one extra IPC
   // round-trip from CompositorBridgeChild to CompositorBridgeParent.
   compositor->RecvClearCachedResources(mLayersId);
 
+  // Hide all plugins in this tab.
+  if (nsCOMPtr<nsIPresShell> shell = GetPresShell()) {
+    if (nsPresContext* presContext = shell->GetPresContext()) {
+      nsRootPresContext* rootPresContext = presContext->GetRootPresContext();
+      nsIFrame* rootFrame = shell->FrameConstructor()->GetRootFrame();
+      rootPresContext->ComputePluginGeometryUpdates(rootFrame, nullptr, nullptr);
+      rootPresContext->ApplyPluginGeometryUpdates();
+    }
+  }
+
   if (mPuppetWidget) {
     mPuppetWidget->Show(false);
   }
 }
 
 NS_IMETHODIMP
 TabChild::GetMessageManager(nsIContentFrameMessageManager** aResult)
 {

--- a/layout/base/nsPresContext.cpp
+++ b/layout/base/nsPresContext.cpp
@@ -2958,29 +2958,32 @@ nsRootPresContext::ComputePluginGeometry
     }
     if (!nsLayoutUtils::IsAncestorFrameCrossDoc(aFrame, f)) {
       // f is not managed by this frame so we should ignore it.
       continue;
     }
     f->SetEmptyWidgetConfiguration();
   }
 
-  nsIFrame* rootFrame = FrameManager()->GetRootFrame();
-
-  if (rootFrame && aBuilder->ContainsPluginItem()) {
-    aBuilder->SetForPluginGeometry();
-    aBuilder->SetAccurateVisibleRegions();
-    // Merging and flattening has already been done and we should not do it
-    // again. nsDisplayScroll(Info)Layer doesn't support trying to flatten
-    // again.
-    aBuilder->SetAllowMergingAndFlattening(false);
-    nsRegion region = rootFrame->GetVisualOverflowRectRelativeToSelf();
-    // nsDisplayPlugin::ComputeVisibility will automatically set a non-hidden
-    // widget configuration for the plugin, if it's visible.
-    aList->ComputeVisibilityForRoot(aBuilder, &region);
+  if (aBuilder) {
+    MOZ_ASSERT(aList);
+    nsIFrame* rootFrame = FrameManager()->GetRootFrame();
+
+    if (rootFrame && aBuilder->ContainsPluginItem()) {
+      aBuilder->SetForPluginGeometry();
+      aBuilder->SetAccurateVisibleRegions();
+      // Merging and flattening has already been done and we should not do it
+      // again. nsDisplayScroll(Info)Layer doesn't support trying to flatten
+      // again.
+      aBuilder->SetAllowMergingAndFlattening(false);
+      nsRegion region = rootFrame->GetVisualOverflowRectRelativeToSelf();
+      // nsDisplayPlugin::ComputeVisibility will automatically set a non-hidden
+      // widget configuration for the plugin, if it's visible.
+      aList->ComputeVisibilityForRoot(aBuilder, &region);
+    }
   }
 
 #ifdef XP_MACOSX
   // We control painting of Mac plugins, so just apply geometry updates now.
   // This is not happening during a paint event.
   ApplyPluginGeometryUpdates();
 #else
   if (XRE_IsParentProcess()) {

--- a/layout/base/nsPresContext.h
+++ b/layout/base/nsPresContext.h
@@ -1519,16 +1519,18 @@ public:
   /**
    * Compute geometry updates for each plugin given that aList is the display
    * list for aFrame. The updates are not yet applied;
    * ApplyPluginGeometryUpdates is responsible for that. In the meantime they
    * are stored on each nsPluginFrame.
    * This needs to be called even when aFrame is a popup, since although
    * windowed plugins aren't allowed in popups, windowless plugins are
    * and ComputePluginGeometryUpdates needs to be called for them.
+   * aBuilder and aList can be null. This indicates that all plugins are
+   * hidden because we're in a background tab.
    */
   void ComputePluginGeometryUpdates(nsIFrame* aFrame,
                                     nsDisplayListBuilder* aBuilder,
                                     nsDisplayList* aList);
 
   /**
    * Apply the stored plugin geometry updates. This should normally be called
    * in DidPaint so the plugins are moved/clipped immediately after we've