Do PPB_FileIO Query and Read in the plugin process.

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>
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/synchronization/condition_variable.h"
 #include "ppapi/c/pp_completion_callback.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/shared_impl/ppapi_shared_export.h"
 #include "ppapi/shared_impl/ppb_message_loop_shared.h"
 
 namespace ppapi {
@@ skipping 55 matching lines @@
   //
   // Run() will invoke the call immediately, if invoked from the target thread
   // (as determined by target_loop_). If invoked on a different thread, the
   // callback will be scheduled to run later on target_loop_.
   void Run(int32_t result);
   // PostRun is like Run(), except it guarantees that the callback will be run
   // later. In particular, if you invoke PostRun on the same thread on which the
   // callback is targeted to run, it will *not* be run immediately.
   void PostRun(int32_t result);
 
-  void BlockUntilRun();
+  // A task to perform cleanup actions or write output params before calling
+  // back to the plugin. The |result| parameter has the current status, e.g.
+  // whether the operation has been aborted. The return value of the task
+  // becomes the final callback result. The task is always called on the same
+  // thread as the callback to the plugin.
+  typedef base::Callback<int32_t(int32_t /* result */)> CompletionTask;
+
+  // Sets a task that is run just before calling back into the plugin. This
+  // should only be called once.
+  void set_completion_task(const CompletionTask& completion_task);
 
   // Returns the ID of the resource which "owns" the callback, or 0 if the
   // callback is not associated with any resource.
   PP_Resource resource_id() const { return resource_id_; }
 
   // Returns true if the callback was completed (possibly aborted).
   bool completed() const { return completed_; }
 
   // 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
@@ skipping 52 matching lines @@
   // Flag used by |PostAbort()| and |PostRun()| to check that we don't schedule
   // the callback more than once.
   bool is_scheduled_;
 
   scoped_refptr<CallbackTracker> tracker_;
   PP_Resource resource_id_;
   bool completed_;
   bool aborted_;
   PP_CompletionCallback callback_;
 
+  // Task to run just before calling back into the plugin.
+  CompletionTask completion_task_;
+
   // The MessageLoopShared on which this callback should be run. This will be
   // NULL if we're in-process.
   scoped_refptr<MessageLoopShared> target_loop_;
 
   int32_t result_for_blocked_callback_;
   // Used for pausing/waking the blocked thread if this is a blocking completion
   // 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_