Move a bunch of code in content\common (as well as a few left in renderer) to the content namespace.

content/worker/worker_thread.h

Index: content/worker/worker_thread.h
===================================================================
--- content/worker/worker_thread.h	(revision 163290)
+++ content/worker/worker_thread.h	(working copy)
@@ -9,13 +9,13 @@
 
 #include "content/common/child_thread.h"
 
-class AppCacheDispatcher;
 class DBMessageFilter;
-class IndexedDBMessageFilter;
 class WebDatabaseObserverImpl;
 struct WorkerProcessMsg_CreateWorker_Params;
 
 namespace content {
+class AppCacheDispatcher;
+class IndexedDBMessageFilter;
 class WebSharedWorkerStub;
 class WorkerWebKitPlatformSupportImpl;