PPAPI: Purposely leak ProxyLock, fix shutdown race

ppapi/shared_impl/ppapi_globals.h

Index: ppapi/shared_impl/ppapi_globals.h
diff --git a/ppapi/shared_impl/ppapi_globals.h b/ppapi/shared_impl/ppapi_globals.h
index 66275e50a7966565b96fafdc29c871a973ba8e21..fdc939a2880baefa822f25c6c336eb7e02a5b2f6 100644
--- a/ppapi/shared_impl/ppapi_globals.h
+++ b/ppapi/shared_impl/ppapi_globals.h
@@ -17,7 +17,6 @@
 #include "ppapi/shared_impl/ppapi_shared_export.h"
 
 namespace base {
-class Lock;
 class MessageLoopProxy;
 class TaskRunner;
 }
@@ -69,8 +68,6 @@ class PPAPI_SHARED_EXPORT PpapiGlobals {
   virtual CallbackTracker* GetCallbackTrackerForInstance(
       PP_Instance instance) = 0;
 
-  virtual base::Lock* GetProxyLock() = 0;
-
   // Logs the given string to the JS console. If "source" is empty, the name of
   // the current module will be used, if it can be determined.
   virtual void LogWithSource(PP_Instance instance,