Add CompletionTask to PPAPI TrackedCallback.

ppapi/shared_impl/tracked_callback.h

Index: ppapi/shared_impl/tracked_callback.h
diff --git a/ppapi/shared_impl/tracked_callback.h b/ppapi/shared_impl/tracked_callback.h
index 4917990e3cfeafa31ebb70623bc4538c1685b3a9..04ffc1ce8f653816212c641af6da9205b1769879 100644
--- a/ppapi/shared_impl/tracked_callback.h
+++ b/ppapi/shared_impl/tracked_callback.h
@@ -9,6 +9,7 @@
 #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"
@@ -84,7 +85,12 @@ class PPAPI_SHARED_EXPORT TrackedCallback
   // callback is targeted to run, it will *not* be run immediately.
   void PostRun(int32_t result);
 
-  void BlockUntilRun();
+  // Task to perform any cleanup or output before calling back into the plugin.

[bbudge, 2013/08/07 21:01:54]

I should add more comments here:
// Task to perform cleanup or write output before calling back into the plugin.
// The |result| parameter can be queried to see if the callback has been
// aborted. The task should return the final result code.  The task is always
// called on the same  thread as the callback to the plugin.

[teravest, 2013/08/08 16:49:52]

Sounds good.

+  typedef base::Callback<int32_t(int32_t /* result */)> CompletionTask;
+
+  // Sets a task that is run just before calling back into the plugin. This can
+  // only be called once.
+  void SetCompletionTask(const CompletionTask& completion_task);

[yzshen1, 2013/08/07 21:09:10]

nit: I think it should be named set_completion_task().

[bbudge, 2013/08/08 18:34:00]

Done.

 
   // Returns the ID of the resource which "owns" the callback, or 0 if the
   // callback is not associated with any resource.
@@ -142,6 +148,8 @@ class PPAPI_SHARED_EXPORT TrackedCallback
   // deleted (so keep a reference if it'll still be needed).
   void MarkAsCompleted();
 
+  int32_t RunCompletionTask(int32_t result);
+
   // This class is ref counted.
   friend class base::RefCountedThreadSafe<TrackedCallback>;
   virtual ~TrackedCallback();
@@ -156,6 +164,9 @@ class PPAPI_SHARED_EXPORT TrackedCallback
   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_;