Move Render(View|Widget)Host and associated classes to content namespace.

chrome/browser/ui/views/extensions/extension_view.h

Index: chrome/browser/ui/views/extensions/extension_view.h
diff --git a/chrome/browser/ui/views/extensions/extension_view.h b/chrome/browser/ui/views/extensions/extension_view.h
index 0ed796232a8564318b2d74e407ba44496ca2501d..660773a1f861d3e5aa1c1b936e457cdff19c4bb7 100644
--- a/chrome/browser/ui/views/extensions/extension_view.h
+++ b/chrome/browser/ui/views/extensions/extension_view.h
@@ -15,7 +15,10 @@ class Browser;
 class Extension;
 class ExtensionHost;
 class ExtensionView;
+
+namespace content {
 class RenderViewHost;
+}
 
 // This handles the display portion of an ExtensionHost.
 class ExtensionView : public views::NativeViewHost {
@@ -35,7 +38,7 @@ class ExtensionView : public views::NativeViewHost {
   ExtensionHost* host() const { return host_; }
   Browser* browser() const { return browser_; }
   const Extension* extension() const;
-  RenderViewHost* render_view_host() const;
+  content::RenderViewHost* render_view_host() const;
   void DidStopLoading();
   void SetIsClipped(bool is_clipped);