Move RenderViewHostObserver to content/public/browser/ and put it into the content namespace.

chrome/browser/prerender/prerender_render_view_host_observer.cc

Index: chrome/browser/prerender/prerender_render_view_host_observer.cc
diff --git a/chrome/browser/prerender/prerender_render_view_host_observer.cc b/chrome/browser/prerender/prerender_render_view_host_observer.cc
index 5be7b3a5624f62e7fd610017f87ef6def0cf4e05..7a5d168725f2a604354daec4069f48e25a30f04e 100644
--- a/chrome/browser/prerender/prerender_render_view_host_observer.cc
+++ b/chrome/browser/prerender/prerender_render_view_host_observer.cc
@@ -13,7 +13,7 @@ namespace prerender {
 PrerenderRenderViewHostObserver::PrerenderRenderViewHostObserver(
     PrerenderContents* prerender_contents,
     RenderViewHost* render_view_host)
-    : RenderViewHostObserver(render_view_host),
+    : content::RenderViewHostObserver(render_view_host),
       prerender_contents_(prerender_contents) {
 }
 
@@ -27,7 +27,7 @@ void PrerenderRenderViewHostObserver::RenderViewHostDestroyed(
 bool PrerenderRenderViewHostObserver::OnMessageReceived(
     const IPC::Message& message) {
   if (!prerender_contents_)
-    return RenderViewHostObserver::OnMessageReceived(message);
+    return content::RenderViewHostObserver::OnMessageReceived(message);
 
   bool handled = true;
   // The following messages we do want to consume.
@@ -42,7 +42,7 @@ bool PrerenderRenderViewHostObserver::OnMessageReceived(
 
   // Pass the message through.
   if (!handled)
-    handled = RenderViewHostObserver::OnMessageReceived(message);
+    handled = content::RenderViewHostObserver::OnMessageReceived(message);
 
   return handled;
 }
@@ -50,7 +50,7 @@ bool PrerenderRenderViewHostObserver::OnMessageReceived(
 // The base class declares this as protected so this is just here to make it
 // public so it is visible to the caller.
 bool PrerenderRenderViewHostObserver::Send(IPC::Message* message) {
-  return RenderViewHostObserver::Send(message);
+  return content::RenderViewHostObserver::Send(message);
 }
 
 void PrerenderRenderViewHostObserver::OnUpdateFaviconURL(