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 5294bde6d9f753d6dcc58603754b7179eb0a3816..64670a09864e51c01013d1159e63236ca4de597c 100644
--- a/cc/ipc/compositor_frame_metadata_struct_traits.cc
+++ b/cc/ipc/compositor_frame_metadata_struct_traits.cc
@@ -29,11 +29,14 @@ bool StructTraits<cc::mojom::CompositorFrameMetadata,
   out->max_page_scale_factor = data.max_page_scale_factor();
   out->root_overflow_x_hidden = data.root_overflow_x_hidden();
   out->root_overflow_y_hidden = data.root_overflow_y_hidden();
-  if (!data.ReadLocationBarOffset(&out->location_bar_offset) ||
-      !data.ReadLocationBarContentTranslation(
-          &out->location_bar_content_translation)) {
+  if (!data.ReadTopControlsHeight(&out->top_controls_height)) {
     return false;
   }
+  out->top_controls_shown_ratio = data.top_controls_shown_ratio();
+  if (!data.ReadBottomControlsHeight(&out->bottom_controls_height)) {
+    return false;
+  }
+  out->bottom_controls_shown_ratio = data.bottom_controls_shown_ratio();
 
   out->root_background_color = data.root_background_color();
   return data.ReadSelection(&out->selection) &&