Fix race conditions in window snapshot code.

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 52 matching lines @@
   // LayerTreeHost::OnCreateAndInitializeOutputSurfaceAttempted with the result.
   virtual void CreateAndInitializeOutputSurface() = 0;
 
   virtual const RendererCapabilities& GetRendererCapabilities() const = 0;
 
   virtual void SetNeedsAnimate() = 0;
   virtual void SetNeedsUpdateLayers() = 0;
   virtual void SetNeedsCommit() = 0;
   virtual void SetNeedsRedraw(gfx::Rect damage_rect) = 0;
   virtual void SetNextCommitWaitsForActivation() = 0;
+  virtual void SetNextCommitForcesRedraw() = 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.
   virtual void SetDeferCommits(bool defer_commits) = 0;
 
   virtual void MainThreadHasStoppedFlinging() = 0;
 
@@ skipping 57 matching lines @@
   explicit DebugScopedSetMainThreadBlocked(Proxy* proxy) {}
   ~DebugScopedSetMainThreadBlocked() {}
  private:
   DISALLOW_COPY_AND_ASSIGN(DebugScopedSetMainThreadBlocked);
 };
 #endif
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROXY_H_