cc: Make async readback path use async glRreadPixels.

cc/trees/thread_proxy.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/thread_proxy.h"
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "cc/base/thread.h"
@@ skipping 528 matching lines @@
   main_thread_weak_ptr_ = weak_factory_.GetWeakPtr();
 
   started_ = true;
 }
 
 void ThreadProxy::Stop() {
   TRACE_EVENT0("cc", "ThreadProxy::Stop");
   DCHECK(IsMainThread());
   DCHECK(started_);
 
-  // Synchronously deletes the impl.
+  // Synchronously finishes pending GL operations and deletes the impl.
   {
     DebugScopedSetMainThreadBlocked main_thread_blocked(this);
 
     CompletionEvent completion;
     Proxy::ImplThread()->PostTask(
+        base::Bind(&ThreadProxy::FinishGLOnImplThread,
+                   impl_thread_weak_ptr_,
+                   &completion));
+    completion.Wait();
+  } {
+    DebugScopedSetMainThreadBlocked main_thread_blocked(this);
+
+    CompletionEvent completion;
+    Proxy::ImplThread()->PostTask(
         base::Bind(&ThreadProxy::LayerTreeHostClosedOnImplThread,
                    impl_thread_weak_ptr_,
                    &completion));
     completion.Wait();
   }
 
   weak_factory_.InvalidateWeakPtrs();
 
   DCHECK(!layer_tree_host_impl_.get());  // verify that the impl deleted.
   layer_tree_host_ = NULL;
@@ skipping 581 matching lines @@
       max_frames_pending = FrameRateController::DEFAULT_MAX_FRAMES_PENDING;
     if (layer_tree_host_impl_->output_surface()->capabilities().
             has_parent_compositor)
       max_frames_pending = 1;
     scheduler_on_impl_thread_->SetMaxFramesPending(max_frames_pending);
   }
 
   completion->Signal();
 }
 
+void ThreadProxy::FinishGLOnImplThread(CompletionEvent* completion) {
+  TRACE_EVENT0("cc", "ThreadProxy::FinishGLOnImplThread");
+  DCHECK(IsImplThread());
+  if (layer_tree_host_impl_->resource_provider())
+    layer_tree_host_impl_->resource_provider()->Finish();
+  completion->Signal();
+}
+
 void ThreadProxy::LayerTreeHostClosedOnImplThread(CompletionEvent* completion) {
   TRACE_EVENT0("cc", "ThreadProxy::LayerTreeHostClosedOnImplThread");
   DCHECK(IsImplThread());
   layer_tree_host_->DeleteContentsTexturesOnImplThread(
       layer_tree_host_impl_->resource_provider());
   layer_tree_host_impl_->EnableVSyncNotification(false);
   input_handler_on_impl_thread_.reset();
   layer_tree_host_impl_.reset();
   scheduler_on_impl_thread_.reset();
   weak_factory_on_impl_thread_.InvalidateWeakPtrs();
@@ skipping 183 matching lines @@
 
 void ThreadProxy::DidReceiveLastInputEventForVSync(
     base::TimeTicks frame_time) {
   if (render_vsync_notification_enabled_) {
     TRACE_EVENT0("cc", "ThreadProxy::DidReceiveLastInputEventForVSync");
     DidVSync(frame_time);
   }
 }
 
 }  // namespace cc