Bug 1287627 - Handle flush TextureHost without composition r=nical

gfx/layers/Compositor.cpp

@@ -55,6 +55,7 @@ void
 Compositor::EndFrame()
 {
   ReadUnlockTextures();
+  mLastCompositionEndTime = TimeStamp::Now();
 }
 
 void
@@ -78,6 +79,18 @@ Compositor::NotifyNotUsedAfterComposition(TextureHost* aTextureHost)
   MOZ_ASSERT(!mIsDestroyed);
 
   mNotifyNotUsedAfterComposition.AppendElement(aTextureHost);
+
+  // If Compositor holds many TextureHosts without compositing,
+  // the TextureHosts should be flushed to reduce memory consumption.
+  const int thresholdCount = 5;
+  const double thresholdSec = 2.0f;
+  if (mNotifyNotUsedAfterComposition.Length() > thresholdCount) {
+    TimeDuration duration = TimeStamp::Now() - mLastCompositionEndTime;
+    // Check if we could flush
+    if (duration.ToSeconds() > thresholdSec) {
+      FlushPendingNotifyNotUsed();
+    }
+  }
 }
 
 void

gfx/layers/Compositor.h

@@ -593,6 +593,11 @@ protected:
    */
   nsTArray<RefPtr<TextureHost>> mNotifyNotUsedAfterComposition;
 
+  /**
+   * Last Composition end time.
+   */
+  TimeStamp mLastCompositionEndTime;
+
   /**
    * Render time for the current composition.
    */