Move remaining files in content\browser\renderer_host to content namespace.

content/browser/renderer_host/render_widget_host_gtk.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_impl.h"
 
 #include "content/port/browser/render_widget_host_view_port.h"
 
-using content::RenderWidgetHostImpl;
+namespace content {
 
 void RenderWidgetHostImpl::OnMsgCreatePluginContainer(
     gfx::PluginWindowHandle id) {
   // TODO(piman): view_ can only be NULL with delayed view creation in
   // extensions (see ExtensionHost::CreateRenderViewSoon). Figure out how to
   // support plugins in that case.
   if (view_) {
     view_->CreatePluginContainer(id);
   } else {
     deferred_plugin_handles_.push_back(id);
   }
 }
 
 void RenderWidgetHostImpl::OnMsgDestroyPluginContainer(
     gfx::PluginWindowHandle id) {
   if (view_) {
     view_->DestroyPluginContainer(id);
   } else {
     for (int i = 0;
          i < static_cast<int>(deferred_plugin_handles_.size());
          i++) {
       if (deferred_plugin_handles_[i] == id) {
         deferred_plugin_handles_.erase(deferred_plugin_handles_.begin() + i);
         i--;
       }
     }
   }
 }
+
+}  // namespace content