Explicitly specify the ui::Compositor to DelegatedFrameHost

ui/compositor/compositor_observer.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/compositor/compositor_observer.h"
 
 #include "base/logging.h"
 
 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);
 }
 
 }