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

content/public/browser/render_view_host_observer.h

Index: content/public/browser/render_view_host_observer.h
diff --git a/content/public/browser/render_view_host_observer.h b/content/public/browser/render_view_host_observer.h
index 1c87dcee172484985b9e2a19b840249baa09a280..a6a1734a04e90754688479151f8254a36722ac75 100644
--- a/content/public/browser/render_view_host_observer.h
+++ b/content/public/browser/render_view_host_observer.h
@@ -10,11 +10,12 @@
 #include "content/common/content_export.h"
 
 class GURL;
-class RenderViewHost;
-class RenderViewHostImpl;
 
 namespace content {
 
+class RenderViewHost;
+class RenderViewHostImpl;
+
 // An observer API implemented by classes which want to filter IPC messages from
 // RenderViewHost.
 class CONTENT_EXPORT RenderViewHostObserver : public IPC::Channel::Listener,
@@ -49,7 +50,7 @@ class CONTENT_EXPORT RenderViewHostObserver : public IPC::Channel::Listener,
   int routing_id() { return routing_id_; }
 
  private:
-  friend class ::RenderViewHostImpl;
+  friend class RenderViewHostImpl;
 
   // Invoked from RenderViewHost. Invokes RenderViewHostDestroyed and NULL out
   // |render_view_host_|.