Support using TrackedCallbacks as hints to determine the handling thread of resource reply messages

ppapi/shared_impl/tracked_callback.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PPAPI_SHARED_IMPL_TRACKED_CALLBACK_H_
 #define PPAPI_SHARED_IMPL_TRACKED_CALLBACK_H_
 
 #include <map>
 #include <set>
 
@@ skipping 95 matching lines @@
   // Returns true if the callback was or should be aborted; this will be the
   // case whenever |Abort()| or |PostAbort()| is called before a non-abortive
   // completion.
   bool aborted() const { return aborted_; }
 
   // Returns true if this is a blocking callback.
   bool is_blocking() {
     return !callback_.func;
   }
 
+  MessageLoopShared* target_loop() const {
+    return target_loop_.get();
+  }
+
   // Determines if the given callback is pending. A callback is pending if it
   // has not completed and has not been aborted. When receiving a plugin call,
   // use this to detect if |callback| represents an operation in progress. When
   // finishing a plugin call, use this to determine whether to write 'out'
   // params and Run |callback|.
   // NOTE: an aborted callback has not necessarily completed, so a false result
   // doesn't imply that the callback has completed.
   // As a convenience, if |callback| is null, this returns false.
   static bool IsPending(const scoped_refptr<TrackedCallback>& callback);
 
@@ skipping 53 matching lines @@
   // callback. Note that in-process, there is no lock, blocking callbacks are
   // not allowed, and therefore this pointer will be NULL.
   scoped_ptr<base::ConditionVariable> operation_completed_condvar_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(TrackedCallback);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_TRACKED_CALLBACK_H_