Introduce bottom controls to CC and let it respond to scrolling

cc/ipc/compositor_frame_metadata_struct_traits.cc

Index: cc/ipc/compositor_frame_metadata_struct_traits.cc
diff --git a/cc/ipc/compositor_frame_metadata_struct_traits.cc b/cc/ipc/compositor_frame_metadata_struct_traits.cc
index ee24b5c2bef0439cb64e322c4ccb6283c4ed9fc4..70aab37d7b5d53afd8c277eea59041de637bf5fa 100644
--- a/cc/ipc/compositor_frame_metadata_struct_traits.cc
+++ b/cc/ipc/compositor_frame_metadata_struct_traits.cc
@@ -32,11 +32,10 @@ bool StructTraits<cc::mojom::CompositorFrameMetadata,
   out->may_contain_video = data.may_contain_video();
   out->is_resourceless_software_draw_with_scroll_or_animation =
       data.is_resourceless_software_draw_with_scroll_or_animation();
-  if (!data.ReadLocationBarOffset(&out->location_bar_offset) ||
-      !data.ReadLocationBarContentTranslation(
-          &out->location_bar_content_translation)) {
-    return false;
-  }
+  out->top_controls_height = data.top_controls_height();
+  out->top_controls_shown_ratio = data.top_controls_shown_ratio();
+  out->bottom_controls_height = data.bottom_controls_height();
+  out->bottom_controls_shown_ratio = data.bottom_controls_shown_ratio();
 
   out->root_background_color = data.root_background_color();
   return data.ReadSelection(&out->selection) &&