Avoid using declarations in headers which introduce symbol conflicts.

third_party/WebKit/Source/modules/device_orientation/DeviceOrientationInspectorAgent.h

 // 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.
 
 #ifndef DeviceOrientationInspectorAgent_h
 #define DeviceOrientationInspectorAgent_h
 
 #include "core/inspector/InspectorBaseAgent.h"
 #include "core/inspector/protocol/DeviceOrientation.h"
 #include "modules/ModulesExport.h"
 
 namespace blink {
 
 class DeviceOrientationController;
 class InspectedFrames;
 
 class MODULES_EXPORT DeviceOrientationInspectorAgent final
     : public InspectorBaseAgent<protocol::DeviceOrientation::Metainfo> {
   WTF_MAKE_NONCOPYABLE(DeviceOrientationInspectorAgent);
 
  public:
   explicit DeviceOrientationInspectorAgent(InspectedFrames*);
   ~DeviceOrientationInspectorAgent() override;
   DECLARE_VIRTUAL_TRACE();
 
   // Protocol methods.
-  Response setDeviceOrientationOverride(double, double, double) override;
-  Response clearDeviceOrientationOverride() override;
+  protocol::Response setDeviceOrientationOverride(double,
+                                                  double,
+                                                  double) override;
+  protocol::Response clearDeviceOrientationOverride() override;
 
-  Response disable() override;
+  protocol::Response disable() override;
   void restore() override;
   void didCommitLoadForLocalFrame(LocalFrame*) override;
 
  private:
   DeviceOrientationController* controller();
 
   Member<InspectedFrames> m_inspectedFrames;
 };
 
 }  // namespace blink
 
 #endif  // !defined(DeviceOrientationInspectorAgent_h)