PPAPI: Make CompletionCallbacks work right on background threads.

ppapi/shared_impl/test_globals.h

Index: ppapi/shared_impl/test_globals.h
diff --git a/ppapi/shared_impl/test_globals.h b/ppapi/shared_impl/test_globals.h
index 36753474b5f9efe6acde3e07d3955601d12df264..ca67e779adf370d58243b3aec1daa6b349832a20 100644
--- a/ppapi/shared_impl/test_globals.h
+++ b/ppapi/shared_impl/test_globals.h
@@ -53,6 +53,10 @@ class TestGlobals : public PpapiGlobals {
                                       PP_LogLevel_Dev level,
                                       const std::string& source,
                                       const std::string& value) OVERRIDE;
+  virtual MessageLoopShared* GetCurrentMessageLoop() OVERRIDE;
+
+  // PpapiGlobals overrides:
+  virtual bool IsHostGlobals() const OVERRIDE;
 
  private:
   ResourceTracker resource_tracker_;