Cleanup: Remove unneeded forward declarations from remoting.

remoting/host/chromoting_host_context.h

Index: remoting/host/chromoting_host_context.h
===================================================================
--- remoting/host/chromoting_host_context.h	(revision 109590)
+++ remoting/host/chromoting_host_context.h	(working copy)
@@ -13,12 +13,6 @@
 #include "base/threading/thread.h"
 #include "remoting/jingle_glue/jingle_thread.h"
 
-class Task;
-
-namespace tracked_objects {
-class Location;
-}
-
 namespace remoting {
 
 // A class that manages threads and running context for the chromoting host
@@ -26,7 +20,7 @@
 class ChromotingHostContext {
  public:
   // Create a context.
-  ChromotingHostContext(base::MessageLoopProxy* ui_message_loop);
+  explicit ChromotingHostContext(base::MessageLoopProxy* ui_message_loop);
   virtual ~ChromotingHostContext();
 
   // TODO(ajwong): Move the Start/Stop methods out of this class. Then