Remove unused includes of plugin_list.h. Also remove unused ContentClient and webkit_support method…

content/public/common/content_client.h

Index: content/public/common/content_client.h
===================================================================
--- content/public/common/content_client.h	(revision 211642)
+++ content/public/common/content_client.h	(working copy)
@@ -39,10 +39,6 @@
 }
 
 namespace webkit {
-namespace npapi {
-class PluginList;
-}
-
 namespace ppapi {
 class HostGlobals;
 }
@@ -110,10 +106,6 @@
   virtual void AddPepperPlugins(
       std::vector<content::PepperPluginInfo>* plugins) {}
 
-  // Gives the embedder a chance to register its own internal NPAPI plugins.
-  virtual void AddNPAPIPlugins(
-      webkit::npapi::PluginList* plugin_list) {}
-
   // Gives the embedder a chance to register its own standard and saveable
   // url schemes early on in the startup sequence.
   virtual void AddAdditionalSchemes(