Discard compositor frames from unloaded web content

cc/ipc/compositor_frame_metadata_struct_traits.cc

 // 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.
 
 #include "cc/ipc/compositor_frame_metadata_struct_traits.h"
 #include "cc/ipc/selection_struct_traits.h"
 #include "cc/ipc/surface_id_struct_traits.h"
 #include "ui/events/mojo/latency_info_struct_traits.h"
 #include "ui/gfx/mojo/selection_bound_struct_traits.h"
 
@@ skipping 18 matching lines @@
   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();
   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();
   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->content_source_id = data.content_source_id();
 
   out->root_background_color = data.root_background_color();
   out->can_activate_before_dependencies =
       data.can_activate_before_dependencies();
   return data.ReadSelection(&out->selection) &&
          data.ReadLatencyInfo(&out->latency_info) &&
          data.ReadReferencedSurfaces(&out->referenced_surfaces);
 }
 
 }  // namespace mojo