Discard compositor frames from unloaded web content

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 4af9b671725620814b3f5d10384a881f4c68d83a..20e835f6f1fdfb91c607ee489b1b5ee144608ce5 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -3607,6 +3607,7 @@ void RenderFrameImpl::didCommitProvisionalLoad(
   // For new page navigations, the browser process needs to be notified of the
   // first paint of that page, so it can cancel the timer that waits for it.
   if (is_main_frame_ && !navigation_state->WasWithinSamePage()) {
+    GetRenderWidget()->IncrementContentSourceId();
     render_view_->QueueMessage(
         new ViewHostMsg_DidFirstPaintAfterLoad(render_view_->routing_id_),
         MESSAGE_DELIVERY_POLICY_WITH_VISUAL_STATE);
@@ -4879,6 +4880,8 @@ void RenderFrameImpl::SendDidCommitProvisionalLoad(
   // corresponding FrameNavigationEntry.
   params.page_state = SingleHistoryItemToPageState(item);
 
+  params.content_source_id = GetRenderWidget()->GetContentSourceId();
+
   params.method = request.httpMethod().latin1();
   if (params.method == "POST")
     params.post_id = ExtractPostId(item);