PPAPI: Make blocking completion callbacks work.

ppapi/thunk/ppb_url_loader_api.h

Index: ppapi/thunk/ppb_url_loader_api.h
diff --git a/ppapi/thunk/ppb_url_loader_api.h b/ppapi/thunk/ppb_url_loader_api.h
index 5f9e58d5aa43c6ab663d5103439dc41978cf934d..0b93fdbfbf84bbc3b1ed5cddf55afb3a339fd494 100644
--- a/ppapi/thunk/ppb_url_loader_api.h
+++ b/ppapi/thunk/ppb_url_loader_api.h
@@ -6,6 +6,7 @@
 #define PPAPI_THUNK_URL_LOADER_API_H_
 
 #include "ppapi/c/ppb_url_loader.h"
+#include "ppapi/shared_impl/api_callback_type.h"
 #include "ppapi/c/trusted/ppb_url_loader_trusted.h"
 
 namespace ppapi {
@@ -16,8 +17,8 @@ class PPB_URLLoader_API {
   virtual ~PPB_URLLoader_API() {}
 
   virtual int32_t Open(PP_Resource request_id,
-                       PP_CompletionCallback callback) = 0;
-  virtual int32_t FollowRedirect(PP_CompletionCallback callback) = 0;
+                       ApiCallbackType callback) = 0;
+  virtual int32_t FollowRedirect(ApiCallbackType callback) = 0;
   virtual PP_Bool GetUploadProgress(int64_t* bytes_sent,
                                     int64_t* total_bytes_to_be_sent) = 0;
   virtual PP_Bool GetDownloadProgress(int64_t* bytes_received,
@@ -25,8 +26,8 @@ class PPB_URLLoader_API {
   virtual PP_Resource GetResponseInfo() = 0;
   virtual int32_t ReadResponseBody(void* buffer,
                                    int32_t bytes_to_read,
-                                   PP_CompletionCallback callback) = 0;
-  virtual int32_t FinishStreamingToFile(PP_CompletionCallback callback) = 0;
+                                   ApiCallbackType callback) = 0;
+  virtual int32_t FinishStreamingToFile(ApiCallbackType callback) = 0;
   virtual void Close() = 0;
 
   // Trusted API.