aura: Track mouse button state.

views/widget/native_widget_aura.cc

 // Copyright (c) 2011 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 "views/widget/native_widget_aura.h"
 
 #include "base/bind.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/desktop.h"
 #include "ui/aura/desktop_observer.h"
@@ skipping 703 matching lines @@
 
 // static
 void NativeWidgetPrivate::ReparentNativeView(gfx::NativeView native_view,
                                              gfx::NativeView new_parent) {
   // http://crbug.com/102576
   NOTIMPLEMENTED();
 }
 
 // static
 bool NativeWidgetPrivate::IsMouseButtonDown() {
-  // http://crbug.com/102577
-  NOTIMPLEMENTED();
-  return false;
+  return aura::Desktop::GetInstance()->IsMouseButtonDown();
 }
 
 }  // namespace internal
 }  // namespace views