Cleanup namespace usage in public/platform/{Web[P-W]*,linux/*}.h

public/platform/WebPermissionCallbacks.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 WebPermissionCallbacks_h
 #define WebPermissionCallbacks_h
 
 #include "WebPrivatePtr.h"
 
-namespace blink {
-class PermissionCallbacks;
-}
-
 namespace WTF { template <typename T> class PassOwnPtr; }
 
 namespace blink {
 
+class PermissionCallbacks;
 class WebPermissionCallbacksPrivate;
 
 class WebPermissionCallbacks {
 public:
     ~WebPermissionCallbacks() { reset(); }
     WebPermissionCallbacks() { }
     WebPermissionCallbacks(const WebPermissionCallbacks& c) { assign(c); }
     WebPermissionCallbacks& operator=(const WebPermissionCallbacks& c)
     {
         assign(c);
         return *this;
     }
 
     BLINK_PLATFORM_EXPORT void reset();
     BLINK_PLATFORM_EXPORT void assign(const WebPermissionCallbacks&);
 
 #if INSIDE_BLINK
-    BLINK_PLATFORM_EXPORT WebPermissionCallbacks(const WTF::PassOwnPtr<blink::PermissionCallbacks>&);
+    BLINK_PLATFORM_EXPORT WebPermissionCallbacks(const WTF::PassOwnPtr<PermissionCallbacks>&);
 #endif
 
     BLINK_PLATFORM_EXPORT void doAllow();
     BLINK_PLATFORM_EXPORT void doDeny();
 
 private:
     WebPrivatePtr<WebPermissionCallbacksPrivate> m_private;
 };
 
 } // namespace blink
 
 #endif