Convert the pp::proxy namespace to the ppapi::proxy namespace.

ppapi/proxy/plugin_var_tracker.cc

Index: ppapi/proxy/plugin_var_tracker.cc
diff --git a/ppapi/proxy/plugin_var_tracker.cc b/ppapi/proxy/plugin_var_tracker.cc
index 0c834a57c09c962545d2dbd89dad20668be33c18..ad8a844985493c6b3dbc45981783a30d967bff4c 100644
--- a/ppapi/proxy/plugin_var_tracker.cc
+++ b/ppapi/proxy/plugin_var_tracker.cc
@@ -13,10 +13,7 @@
 #include "ppapi/proxy/proxy_object_var.h"
 #include "ppapi/shared_impl/var.h"
 
-using ppapi::ProxyObjectVar;
-using ppapi::Var;
-
-namespace pp {
+namespace ppapi {
 namespace proxy {
 
 PluginVarTracker::HostVar::HostVar(PluginDispatcher* d, int32 i)
@@ -276,4 +273,4 @@ scoped_refptr<ProxyObjectVar> PluginVarTracker::FindOrMakePluginVarFromHostVar(
 }
 
 }  // namesace proxy
-}  // namespace pp
+}  // namespace ppapi