CHECK that the RendererCompositorFrameSink has been detached

content/renderer/gpu/renderer_compositor_frame_sink.cc

Index: content/renderer/gpu/renderer_compositor_frame_sink.cc
diff --git a/content/renderer/gpu/renderer_compositor_frame_sink.cc b/content/renderer/gpu/renderer_compositor_frame_sink.cc
index 16ccae09e0618e338d0de11d2f4676883ea6cb42..2fafbf0613a132efe335d133ce594052dfcbd706 100644
--- a/content/renderer/gpu/renderer_compositor_frame_sink.cc
+++ b/content/renderer/gpu/renderer_compositor_frame_sink.cc
@@ -74,7 +74,11 @@ RendererCompositorFrameSink::RendererCompositorFrameSink(
   thread_checker_.DetachFromThread();
 }
 
-RendererCompositorFrameSink::~RendererCompositorFrameSink() = default;
+RendererCompositorFrameSink::~RendererCompositorFrameSink() {
+  // TODO(crbug.com/702764): If not detached then IPC messages would crash
+  // after this class is destroyed.
+  CHECK(!bound_);
+}
 
 bool RendererCompositorFrameSink::BindToClient(
     cc::CompositorFrameSinkClient* client) {
@@ -91,6 +95,7 @@ bool RendererCompositorFrameSink::BindToClient(
                  compositor_frame_sink_proxy_);
   compositor_frame_sink_filter_->AddHandlerOnCompositorThread(
       routing_id_, compositor_frame_sink_filter_handler_);
+  bound_ = true;
   return true;
 }
 
@@ -105,6 +110,7 @@ void RendererCompositorFrameSink::DetachFromClient() {
       routing_id_, compositor_frame_sink_filter_handler_);
 
   cc::CompositorFrameSink::DetachFromClient();
+  bound_ = false;
 }
 
 void RendererCompositorFrameSink::SubmitCompositorFrame(