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

cc/trees/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_THREAD_PROXY_H_
 #define CC_TREES_THREAD_PROXY_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 148 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 void SetDebugState(const LayerTreeDebugState& debug_state) OVERRIDE;
   virtual scoped_ptr<base::Value> AsValue() const OVERRIDE;
   virtual bool CommitPendingForTesting() OVERRIDE;
   virtual scoped_ptr<base::Value> SchedulerAsValueForTesting() OVERRIDE;
 
   // LayerTreeHostImplClient implementation
   virtual void UpdateRendererCapabilitiesOnImplThread() OVERRIDE;
   virtual void DidLoseOutputSurfaceOnImplThread() OVERRIDE;
   virtual void CommitVSyncParameters(base::TimeTicks timebase,
                                      base::TimeDelta interval) OVERRIDE;
@@ skipping 116 matching lines @@
 
   base::WeakPtr<ThreadProxy> main_thread_weak_ptr_;
   base::WeakPtr<ThreadProxy> impl_thread_weak_ptr_;
 
   DISALLOW_COPY_AND_ASSIGN(ThreadProxy);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_THREAD_PROXY_H_