Explicitly specify the ui::Compositor to DelegatedFrameHost

ui/compositor/compositor_observer.cc

Index: ui/compositor/compositor_observer.cc
diff --git a/ui/compositor/compositor_observer.cc b/ui/compositor/compositor_observer.cc
index 209cd5220b38b46c6c206447e39c75795379554f..f6192a221dc69602f33dbd98c1510af2d2689702 100644
--- a/ui/compositor/compositor_observer.cc
+++ b/ui/compositor/compositor_observer.cc
@@ -8,20 +8,10 @@
 
 namespace ui {
 
-#if defined(OS_MACOSX)
-// Debugging instrumentation for crbug.com/401630.
-// TODO(ccameron): remove this.
 CompositorObserver::CompositorObserver() : observing_count_(0) {}
-#else
-CompositorObserver::CompositorObserver() {}
-#endif
 
 CompositorObserver::~CompositorObserver() {
-#if defined(OS_MACOSX)
-  // Debugging instrumentation for crbug.com/401630.
-  // TODO(ccameron): remove this.
-  CHECK_EQ(observing_count_, 0);
-#endif
+  DCHECK_EQ(observing_count_, 0);
 }
 
 }