Avoid using declarations in headers which introduce symbol conflicts.

third_party/WebKit/Source/web/InspectorRenderingAgent.cpp

 // Copyright 2015 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 "web/InspectorRenderingAgent.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/Settings.h"
 #include "core/page/Page.h"
 #include "web/InspectorOverlay.h"
 #include "web/WebLocalFrameImpl.h"
 #include "web/WebViewImpl.h"
 
 namespace blink {
 
+using protocol::Response;
+
 namespace RenderingAgentState {
 static const char showDebugBorders[] = "showDebugBorders";
 static const char showFPSCounter[] = "showFPSCounter";
 static const char showPaintRects[] = "showPaintRects";
 static const char showScrollBottleneckRects[] = "showScrollBottleneckRects";
 static const char showSizeOnResize[] = "showSizeOnResize";
 }
 
 InspectorRenderingAgent* InspectorRenderingAgent::create(
     WebLocalFrameImpl* webLocalFrameImpl,
@@ skipping 86 matching lines @@
   return Response::OK();
 }
 
 DEFINE_TRACE(InspectorRenderingAgent) {
   visitor->trace(m_webLocalFrameImpl);
   visitor->trace(m_overlay);
   InspectorBaseAgent::trace(visitor);
 }
 
 }  // namespace blink