Enable MSVC warning for unused locals.

content/browser/renderer_host/render_widget_host_view_aura.cc

 // Copyright (c) 2012 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 "content/browser/renderer_host/render_widget_host_view_aura.h"
 
 #include "base/auto_reset.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 652 matching lines @@
     return reinterpret_cast<gfx::NativeViewId>(host->GetAcceleratedWidget());
 #endif
   return static_cast<gfx::NativeViewId>(NULL);
 }
 
 gfx::NativeViewAccessible RenderWidgetHostViewAura::GetNativeViewAccessible() {
 #if defined(OS_WIN)
   aura::WindowTreeHost* host = window_->GetHost();
   if (!host)
     return static_cast<gfx::NativeViewAccessible>(NULL);
-  HWND hwnd = host->GetAcceleratedWidget();
+  // ?? Should this use host instead of host_?

[Peter Kasting, 2014/11/18 00:41:03]

This needs to be answered before landing.

I have no idea what the difference is.  Code in this file uses both frequently,
which confuses me to no end.

   BrowserAccessibilityManager* manager =
       host_->GetOrCreateRootBrowserAccessibilityManager();
   if (manager)
     return manager->GetRoot()->ToBrowserAccessibilityWin();
 #endif
 
   NOTIMPLEMENTED();
   return static_cast<gfx::NativeViewAccessible>(NULL);
 }
 
@@ skipping 1868 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewBase, public:
 
 // static
 void RenderWidgetHostViewBase::GetDefaultScreenInfo(WebScreenInfo* results) {
   GetScreenInfoForWindow(results, NULL);
 }
 
 }  // namespace content