Made double-tap zoom work in pinch virtual viewport mode (Chromium-side).

ui/compositor/compositor.h

 // Copyright (c) 2012 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 UI_COMPOSITOR_COMPOSITOR_H_
 #define UI_COMPOSITOR_COMPOSITOR_H_
 
 #include <string>
 
 #include "base/containers/hash_tables.h"
@@ skipping 215 matching lines @@
 
   // Signals swap has aborted (e.g. lost context).
   void OnSwapBuffersAborted();
 
   // LayerTreeHostClient implementation.
   virtual void WillBeginMainFrame(int frame_id) OVERRIDE {}
   virtual void DidBeginMainFrame() OVERRIDE {}
   virtual void BeginMainFrame(const cc::BeginFrameArgs& args) OVERRIDE;
   virtual void Layout() OVERRIDE;
   virtual void ApplyViewportDeltas(
+      const gfx::Vector2d& inner_delta,
+      const gfx::Vector2d& outer_delta,
+      float page_scale,
+      float top_controls_delta) OVERRIDE {}
+  virtual void ApplyViewportDeltas(
       const gfx::Vector2d& scroll_delta,
       float page_scale,
       float top_controls_delta) OVERRIDE {}
   virtual scoped_ptr<cc::OutputSurface> CreateOutputSurface(bool fallback)
       OVERRIDE;
   virtual void DidInitializeOutputSurface() OVERRIDE {}
   virtual void WillCommit() OVERRIDE {}
   virtual void DidCommit() OVERRIDE;
   virtual void DidCommitAndDrawFrame() OVERRIDE;
   virtual void DidCompleteSwapBuffers() OVERRIDE;
@@ skipping 71 matching lines @@
   LayerAnimatorCollection layer_animator_collection_;
 
   base::WeakPtrFactory<Compositor> schedule_draw_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Compositor);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_COMPOSITOR_H_