Remove PCompositable::DestroySync. (bug 1301780 part 2, r=nical)

gfx/layers/IPDLActor.h

@@ -115,27 +115,19 @@ public:
 
   virtual bool RecvDestroy() override
   {
-    if (!mDestroyed) {
-      Destroy();
-      mDestroyed = true;
-    }
+    DestroyIfNeeded();
     Unused << Protocol::Send__delete__(this);
     return true;
   }
 
-  virtual bool RecvDestroySync() override
-  {
-    if (!mDestroyed) {
-      Destroy();
-      mDestroyed = true;
-    }
-    return true;
-  }
-
   typedef ipc::IProtocolManager<ipc::IProtocol>::ActorDestroyReason Why;
 
-  virtual void ActorDestroy(Why) override
-  {
+  virtual void ActorDestroy(Why) override {
+    DestroyIfNeeded();
+  }
+
+protected:
+  void DestroyIfNeeded() {
     if (!mDestroyed) {
       Destroy();
       mDestroyed = true;

gfx/layers/composite/TextureHost.cpp

@@ -85,6 +85,11 @@ public:
 
   uint64_t GetSerial() const { return mSerial; }
 
+  virtual bool RecvDestroySync() override {
+    DestroyIfNeeded();
+    return true;
+  }
+
   HostIPCAllocator* mSurfaceAllocator;
   RefPtr<TextureHost> mTextureHost;
   // mSerial is unique in TextureClient's process.

gfx/layers/ipc/PCompositable.ipdl

@@ -22,11 +22,6 @@ parent:
      * Asynchronously tell the compositor side to remove the texture.
      */
     async Destroy();
-
-    /**
-     * Never used (needed for ParentActor).
-     */
-    async DestroySync();
 };
 
 } // namespace