cc: Disallow scroll offset animations when impl-scrolling isn't supported

cc/trees/single_thread_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_SINGLE_THREAD_PROXY_H_
 #define CC_TREES_SINGLE_THREAD_PROXY_H_
 
 #include <limits>
 
 #include "base/time/time.h"
@@ skipping 29 matching lines @@
   virtual void SetNextCommitWaitsForActivation() OVERRIDE;
   virtual void NotifyInputThrottledUntilCommit() OVERRIDE {}
   virtual void SetDeferCommits(bool defer_commits) OVERRIDE;
   virtual bool CommitRequested() const OVERRIDE;
   virtual bool BeginMainFrameRequested() const OVERRIDE;
   virtual void MainThreadHasStoppedFlinging() OVERRIDE {}
   virtual void Start() OVERRIDE;
   virtual void Stop() OVERRIDE;
   virtual size_t MaxPartialTextureUpdates() const OVERRIDE;
   virtual void ForceSerializeOnSwapBuffers() OVERRIDE;
+  virtual bool SupportsImplScrolling() const OVERRIDE;
   virtual scoped_ptr<base::Value> AsValue() const OVERRIDE;
   virtual bool CommitPendingForTesting() OVERRIDE;
 
   // LayerTreeHostImplClient implementation
   virtual void UpdateRendererCapabilitiesOnImplThread() OVERRIDE;
   virtual void DidLoseOutputSurfaceOnImplThread() OVERRIDE;
   virtual void CommitVSyncParameters(base::TimeTicks timebase,
                                      base::TimeDelta interval) OVERRIDE {}
   virtual void SetEstimatedParentDrawTime(base::TimeDelta draw_time) OVERRIDE {}
   virtual void SetMaxSwapsPendingOnImplThread(int max) OVERRIDE {}
@@ skipping 115 matching lines @@
  private:
   DebugScopedSetImplThread impl_thread_;
   DebugScopedSetMainThreadBlocked main_thread_blocked_;
 
   DISALLOW_COPY_AND_ASSIGN(DebugScopedSetImplThreadAndMainThreadBlocked);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_SINGLE_THREAD_PROXY_H_