Allow ui::Compositor to disable commits during tab-switch

cc/trees/proxy.h

 // 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.
 
 #ifndef CC_TREES_PROXY_H_
 #define CC_TREES_PROXY_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 62 matching lines @@
   virtual const RendererCapabilities& GetRendererCapabilities() const = 0;
 
   virtual void SetNeedsAnimate() = 0;
   virtual void SetNeedsUpdateLayers() = 0;
   virtual void SetNeedsCommit() = 0;
   virtual void SetNeedsRedraw(const gfx::Rect& damage_rect) = 0;
   virtual void SetNextCommitWaitsForActivation() = 0;
 
   virtual void NotifyInputThrottledUntilCommit() = 0;
 
-  // Defers commits until it is reset. It is only supported when in threaded
-  // mode. It's an error to make a sync call like CompositeAndReadback while
-  // commits are deferred.
+  // Defers commits until it is reset. It is only supported when using a
+  // scheduler.
   virtual void SetDeferCommits(bool defer_commits) = 0;
 
   virtual void MainThreadHasStoppedFlinging() = 0;
 
   virtual bool CommitRequested() const = 0;
   virtual bool BeginMainFrameRequested() const = 0;
 
   // Must be called before using the proxy.
   virtual void Start() = 0;
   virtual void Stop() = 0;   // Must be called before deleting the proxy.
@@ skipping 60 matching lines @@
   explicit DebugScopedSetMainThreadBlocked(Proxy* proxy) {}
   ~DebugScopedSetMainThreadBlocked() {}
  private:
   DISALLOW_COPY_AND_ASSIGN(DebugScopedSetMainThreadBlocked);
 };
 #endif
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROXY_H_