Make cc::CompositorFrames movable [Part 1 of 2]

content/public/browser/android/synchronous_compositor.h

 // Copyright 2013 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 CONTENT_PUBLIC_BROWSER_ANDROID_SYNCHRONOUS_COMPOSITOR_H_
 #define CONTENT_PUBLIC_BROWSER_ANDROID_SYNCHRONOUS_COMPOSITOR_H_
 
 #include <stddef.h>
 
 #include <memory>
 
 #include "base/memory/ref_counted.h"
+#include "base/optional.h"
 #include "base/time/time.h"
+#include "cc/output/compositor_frame.h"
 #include "content/common/content_export.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 
 class SkCanvas;
 
 namespace cc {
-class CompositorFrame;
 class CompositorFrameAck;
 }
 
 namespace gfx {
 class Point;
 class ScrollOffset;
 class Transform;
 };
 
 namespace content {
@@ skipping 13 matching lines @@
 
   struct Frame {
     Frame();
     ~Frame();
 
     // Movable type.
     Frame(Frame&& rhs);
     Frame& operator=(Frame&& rhs);
 
     uint32_t output_surface_id;
-    std::unique_ptr<cc::CompositorFrame> frame;
+    base::Optional<cc::CompositorFrame> frame;
 
    private:
     DISALLOW_COPY_AND_ASSIGN(Frame);
   };
 
   // "On demand" hardware draw. The content is first clipped to |damage_area|,
   // then transformed through |transform|, and finally clipped to |view_size|.
   virtual Frame DemandDrawHw(
       const gfx::Size& surface_size,
       const gfx::Transform& transform,
@@ skipping 28 matching lines @@
   // and if any input animation is active, it should tick now.
   virtual void OnComputeScroll(base::TimeTicks animation_time) = 0;
 
  protected:
   virtual ~SynchronousCompositor() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_ANDROID_SYNCHRONOUS_COMPOSITOR_H_