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

cc/output/compositor_frame_metadata.cc

 // 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.
 
 #include "cc/output/compositor_frame_metadata.h"
 
 namespace cc {
 
 CompositorFrameMetadata::CompositorFrameMetadata()
     : device_scale_factor(0.f),
       page_scale_factor(0.f),
       min_page_scale_factor(0.f),
       max_page_scale_factor(0.f),
       root_overflow_x_hidden(false),
       root_overflow_y_hidden(false),
       root_background_color(SK_ColorWHITE) {}
 
 CompositorFrameMetadata::CompositorFrameMetadata(
+    CompositorFrameMetadata&& other) = default;
+
+CompositorFrameMetadata::~CompositorFrameMetadata() {
+}
+
+CompositorFrameMetadata& CompositorFrameMetadata::operator=(
+    CompositorFrameMetadata&& other) = default;
+
+CompositorFrameMetadata CompositorFrameMetadata::Clone() const {
+  CompositorFrameMetadata metadata(*this);
+  return metadata;
+}
+
+CompositorFrameMetadata::CompositorFrameMetadata(
     const CompositorFrameMetadata& other) = default;
 
-CompositorFrameMetadata::~CompositorFrameMetadata() {
-}
-
 }  // namespace cc