(Reland) Discard compositor frames from unloaded web content

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1563 matching lines @@
   metadata.max_page_scale_factor = active_tree_->max_page_scale_factor();
   metadata.top_controls_height =
       browser_controls_offset_manager_->TopControlsHeight();
   metadata.top_controls_shown_ratio =
       browser_controls_offset_manager_->TopControlsShownRatio();
   metadata.bottom_controls_height =
       browser_controls_offset_manager_->BottomControlsHeight();
   metadata.bottom_controls_shown_ratio =
       browser_controls_offset_manager_->BottomControlsShownRatio();
   metadata.root_background_color = active_tree_->background_color();
+  metadata.content_source_id = active_tree_->content_source_id();
 
   active_tree_->GetViewportSelection(&metadata.selection);
 
   if (OuterViewportScrollLayer()) {
     metadata.root_overflow_x_hidden =
         !OuterViewportScrollLayer()->user_scrollable_horizontal();
     metadata.root_overflow_y_hidden =
         !OuterViewportScrollLayer()->user_scrollable_vertical();
   }
 
@@ skipping 2565 matching lines @@
       worker_context_visibility_ =
           worker_context->CacheController()->ClientBecameVisible();
     } else {
       worker_context->CacheController()->ClientBecameNotVisible(
           std::move(worker_context_visibility_));
     }
   }
 }
 
 }  // namespace cc