Make it possible to cancel commits following an animation

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 <algorithm>
 #include <string>
 
 #include "base/auto_reset.h"
@@ skipping 363 matching lines @@
   return main().renderer_capabilities_main_thread_copy;
 }
 
 void ThreadProxy::SetNeedsAnimate() {
   DCHECK(IsMainThread());
   if (main().animate_requested)
     return;
 
   TRACE_EVENT0("cc", "ThreadProxy::SetNeedsAnimate");
   main().animate_requested = true;
-  main().can_cancel_commit = false;
+  main().can_cancel_commit = true;
   SendCommitRequestToImplThreadIfNeeded();
 }
 
 void ThreadProxy::SetNeedsUpdateLayers() {
   DCHECK(IsMainThread());
 
   if (main().commit_request_sent_to_impl_thread)
     return;
   TRACE_EVENT0("cc", "ThreadProxy::SetNeedsUpdateLayers");
 
@@ skipping 509 matching lines @@
       make_scoped_ptr(new ResourceUpdateQueue);
 
   bool updated = layer_tree_host()->UpdateLayers(queue.get());
 
   // Once single buffered layers are committed, they cannot be modified until
   // they are drawn by the impl thread.
   main().textures_acquired = false;
 
   layer_tree_host()->WillCommit();
 
+  // Before calling animate, we set main().animate_requested to false. If it is
+  // true now, it means SetNeedAnimate was called again, but during a state when
+  // main().commit_request_sent_to_impl_thread = true. We need to force that
+  // call to happen again now so that the commit request is sent to the impl
+  // thread.
+  if (main().animate_requested) {
+    // Forces SetNeedsAnimate to consider posting a commit task.
+    main().animate_requested = false;
+    SetNeedsAnimate();
+  }
+
   if (!updated && can_cancel_this_commit) {
     TRACE_EVENT_INSTANT0("cc", "EarlyOut_NoUpdates", TRACE_EVENT_SCOPE_THREAD);
     bool did_handle = true;
     Proxy::ImplThreadTaskRunner()->PostTask(
         FROM_HERE,
         base::Bind(&ThreadProxy::BeginMainFrameAbortedOnImplThread,
                    impl_thread_weak_ptr_,
                    did_handle));
 
     // Although the commit is internally aborted, this is because it has been
     // detected to be a no-op.  From the perspective of an embedder, this commit
     // went through, and input should no longer be throttled, etc.
     layer_tree_host()->CommitComplete();
     layer_tree_host()->DidBeginMainFrame();
     return;
   }
 
-  // Before calling animate, we set main().animate_requested to false. If it is
-  // true
-  // now, it means SetNeedAnimate was called again, but during a state when
-  // main().commit_request_sent_to_impl_thread = true. We need to force that
-  // call to
-  // happen again now so that the commit request is sent to the impl thread.
-  if (main().animate_requested) {
-    // Forces SetNeedsAnimate to consider posting a commit task.
-    main().animate_requested = false;
-    SetNeedsAnimate();
-  }
-
   scoped_refptr<ContextProvider> offscreen_context_provider;
   if (main().renderer_capabilities_main_thread_copy.using_offscreen_context3d &&
       layer_tree_host()->needs_offscreen_context()) {
     offscreen_context_provider =
         layer_tree_host()->client()->OffscreenContextProvider();
     if (offscreen_context_provider.get())
       main().created_offscreen_context_provider = true;
   }
 
   // Notify the impl thread that the main thread is ready to commit. This will
@@ skipping 780 matching lines @@
 
   impl().timing_history.DidActivatePendingTree();
 }
 
 void ThreadProxy::DidManageTiles() {
   DCHECK(IsImplThread());
   impl().scheduler->DidManageTiles();
 }
 
 }  // namespace cc