Revert of Enable BeginFrame scheduling on aura

content/browser/renderer_host/begin_frame_observer_proxy.cc

Index: content/browser/renderer_host/begin_frame_observer_proxy.cc
diff --git a/content/browser/renderer_host/begin_frame_observer_proxy.cc b/content/browser/renderer_host/begin_frame_observer_proxy.cc
index 06baa18bd2a128390dd6436cf581077043c0f5fc..7a6651f53c3a9faf6d55e981e1838d333563dd5a 100644
--- a/content/browser/renderer_host/begin_frame_observer_proxy.cc
+++ b/content/browser/renderer_host/begin_frame_observer_proxy.cc
@@ -14,7 +14,6 @@
 }
 
 BeginFrameObserverProxy::~BeginFrameObserverProxy() {
-  DCHECK(!compositor_);
 }
 
 void BeginFrameObserverProxy::SetNeedsBeginFrames(bool needs_begin_frames) {
@@ -39,7 +38,6 @@
   DCHECK(compositor);
 
   compositor_ = compositor;
-  compositor_->AddObserver(this);
   if (needs_begin_frames_)
     StartObservingBeginFrames();
 }
@@ -47,7 +45,6 @@
 void BeginFrameObserverProxy::ResetCompositor() {
   if (!compositor_)
     return;
-  compositor_->RemoveObserver(this);
 
   if (needs_begin_frames_)
     StopObservingBeginFrames();
@@ -58,11 +55,6 @@
   if (last_sent_begin_frame_args_.frame_time != args.frame_time)
     client_->SendBeginFrame(args);
   last_sent_begin_frame_args_ = args;
-}
-
-void BeginFrameObserverProxy::OnCompositingShuttingDown(
-    ui::Compositor* compositor) {
-  ResetCompositor();
 }
 
 void BeginFrameObserverProxy::StartObservingBeginFrames() {