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

ppapi/proxy/ppb_file_system_proxy.h

Index: ppapi/proxy/ppb_file_system_proxy.h
diff --git a/ppapi/proxy/ppb_file_system_proxy.h b/ppapi/proxy/ppb_file_system_proxy.h
index 795abcb938905782cdcf8fa372d00adf2fc0e9d9..b83fb992932ea40bc416f6593d7bb9e6bc6cec9c 100644
--- a/ppapi/proxy/ppb_file_system_proxy.h
+++ b/ppapi/proxy/ppb_file_system_proxy.h
@@ -19,10 +19,9 @@
 struct PPB_FileSystem_Dev;
 
 namespace ppapi {
+
 class HostResource;
-}
 
-namespace pp {
 namespace proxy {
 
 class PPB_FileSystem_Proxy : public InterfaceProxy {
@@ -52,13 +51,13 @@ class PPB_FileSystem_Proxy : public InterfaceProxy {
   void OpenCompleteInHost(int32_t result,
                           const ppapi::HostResource& host_resource);
 
-  CompletionCallbackFactory<PPB_FileSystem_Proxy,
-                            ProxyNonThreadSafeRefCount> callback_factory_;
+  pp::CompletionCallbackFactory<PPB_FileSystem_Proxy,
+                                ProxyNonThreadSafeRefCount> callback_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_FileSystem_Proxy);
 };
 
 }  // namespace proxy
-}  // namespace pp
+}  // namespace ppapi
 
 #endif  // PPAPI_PROXY_PPB_FILE_SYSTEM_PROXY_H_