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

ppapi/proxy/ppb_core_proxy.cc

Index: ppapi/proxy/ppb_core_proxy.cc
diff --git a/ppapi/proxy/ppb_core_proxy.cc b/ppapi/proxy/ppb_core_proxy.cc
index 41b330132ab303a8de60dc0bc1cf8988ce76958f..3c6aa4bd5ea5af342abd16532e8acdaed1355753 100644
--- a/ppapi/proxy/ppb_core_proxy.cc
+++ b/ppapi/proxy/ppb_core_proxy.cc
@@ -19,11 +19,7 @@
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/shared_impl/time_conversion.h"
 
-using ppapi::HostResource;
-using ppapi::TimeToPPTime;
-using ppapi::TimeTicksToPPTimeTicks;
-
-namespace pp {
+namespace ppapi {
 namespace proxy {
 
 namespace {
@@ -128,4 +124,4 @@ void PPB_Core_Proxy::OnMsgReleaseResource(const HostResource& resource) {
 }
 
 }  // namespace proxy
-}  // namespace pp
+}  // namespace ppapi