Remove default begin frame sources from the renderer

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index fecc962a4097ce95c0e0b8cba14999138c933fd9..bdcda596ebb2593034e4c8a8b62802ed15fb194d 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -1618,6 +1618,17 @@ blink::scheduler::RendererScheduler* RenderThreadImpl::GetRendererScheduler() {
 
 std::unique_ptr<cc::BeginFrameSource>
 RenderThreadImpl::CreateExternalBeginFrameSource(int routing_id) {
+  const base::CommandLine* command_line =
+      base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kIsRunningInMash) ||
+      command_line->HasSwitch(cc::switches::kDisableBeginFrameScheduling)) {
+    return base::WrapUnique(new cc::DelayBasedBeginFrameSource(
+        base::MakeUnique<cc::DelayBasedTimeSource>(
+            compositor_task_runner_
+                ? compositor_task_runner_.get()
+                : main_thread_compositor_task_runner_.get())));
+  }
+
   return base::WrapUnique(new CompositorExternalBeginFrameSource(
       compositor_message_filter_.get(), sync_message_filter(), routing_id));
 }