Introduce bottom controls to CC and let it respond to scrolling

cc/ipc/compositor_frame_metadata_struct_traits.h

 // Copyright 2016 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_IPC_COMPOSITOR_FRAME_METADATA_STRUCT_TRAITS_H_
 #define CC_IPC_COMPOSITOR_FRAME_METADATA_STRUCT_TRAITS_H_
 
 #include "cc/ipc/compositor_frame_metadata.mojom.h"
 #include "cc/output/compositor_frame_metadata.h"
 
@@ skipping 39 matching lines @@
   static bool root_overflow_x_hidden(
       const cc::CompositorFrameMetadata& metadata) {
     return metadata.root_overflow_x_hidden;
   }
 
   static bool root_overflow_y_hidden(
       const cc::CompositorFrameMetadata& metadata) {
     return metadata.root_overflow_y_hidden;
   }
 
-  static gfx::Vector2dF location_bar_offset(
+  static gfx::Vector2dF top_controls_height(
       const cc::CompositorFrameMetadata& metadata) {
-    return metadata.location_bar_offset;
+    return metadata.top_controls_height;
   }
 
-  static gfx::Vector2dF location_bar_content_translation(
+  static float top_controls_shown_ratio(
       const cc::CompositorFrameMetadata& metadata) {
-    return metadata.location_bar_content_translation;
+    return metadata.top_controls_shown_ratio;
+  }
+
+  static gfx::Vector2dF bottom_controls_height(
+      const cc::CompositorFrameMetadata& metadata) {
+    return metadata.bottom_controls_height;
+  }
+
+  static float bottom_controls_shown_ratio(
+      const cc::CompositorFrameMetadata& metadata) {
+    return metadata.bottom_controls_shown_ratio;
   }
 
   static uint32_t root_background_color(
       const cc::CompositorFrameMetadata& metadata) {
     return metadata.root_background_color;
   }
 
   static const cc::Selection<gfx::SelectionBound>& selection(
       const cc::CompositorFrameMetadata& metadata) {
     return metadata.selection;
@@ skipping 14 matching lines @@
     return metadata.referenced_surfaces;
   }
 
   static bool Read(cc::mojom::CompositorFrameMetadataDataView data,
                    cc::CompositorFrameMetadata* out);
 };
 
 }  // namespace mojo
 
 #endif  // CC_IPC_COMPOSITOR_FRAME_METADATA_STRUCT_TRAITS_H_