[cc]: Add a BeginMainFrameNotExpectedSoon signal and route it to the RendererScheduler.

content/renderer/gpu/render_widget_compositor.cc

Index: content/renderer/gpu/render_widget_compositor.cc
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index e3cb405a68357be49fd66a1a8d1dce4f1b46df28..86e01daaf64a6565fc10c47489787a69c6bee79f 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -772,6 +772,10 @@ void RenderWidgetCompositor::BeginMainFrame(const cc::BeginFrameArgs& args) {
   widget_->webwidget()->beginFrame(web_begin_frame_args);
 }
 
+void RenderWidgetCompositor::BeginMainFrameNoLongerRequired() {
+  compositor_deps_->GetRendererScheduler()->BeginFrameNoLongerRequired();
+}
+
 void RenderWidgetCompositor::Layout() {
   widget_->webwidget()->layout();