Add debug shortcuts that toggles options to shows paint rects

ui/compositor/compositor.cc

Index: ui/compositor/compositor.cc
diff --git a/ui/compositor/compositor.cc b/ui/compositor/compositor.cc
index 6f65e8a78a11d0b4a80fc80471a8cca6311c0aa2..8477cfb217349b8c5a6de5d7bf8008d4ad30a106 100644
--- a/ui/compositor/compositor.cc
+++ b/ui/compositor/compositor.cc
@@ -757,6 +757,15 @@ Compositor::OffscreenContextProviderForCompositorThread() {
       OffscreenContextProviderForCompositorThread();
 }
 
+const cc::LayerTreeDebugState& Compositor::GetLayerTreeDebugState() const {
+  return host_->debug_state();
+}
+
+void Compositor::SetLayerTreeDebugState(
+    const cc::LayerTreeDebugState& debug_state) {
+  host_->SetDebugState(debug_state);
+}
+
 scoped_refptr<CompositorLock> Compositor::GetCompositorLock() {
   if (!compositor_lock_) {
     compositor_lock_ = new CompositorLock(this);