PPAPI: Make CompletionCallbacks work right on background threads.

ppapi/shared_impl/ppapi_globals.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_PPAPI_GLOBALS_H_
 #define PPAPI_SHARED_IMPL_PPAPI_GLOBALS_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/thread_local.h"  // For testing purposes only.
 #include "ppapi/c/dev/ppb_console_dev.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_module.h"
 #include "ppapi/shared_impl/api_id.h"
 #include "ppapi/shared_impl/ppapi_shared_export.h"
 
 namespace base {
 class Lock;
 class MessageLoopProxy;
 }
 
 namespace ppapi {
 
 class CallbackTracker;
+class MessageLoopShared;
 class ResourceTracker;
 class VarTracker;
 
 namespace thunk {
 class PPB_Instance_API;
 class ResourceCreationAPI;
 }
 
 // Abstract base class
 class PPAPI_SHARED_EXPORT PpapiGlobals {
  public:
+  // Must be created on the main thread.
   PpapiGlobals();
 
   // This constructor is to be used only for making a PpapiGlobal for testing
   // purposes. This avoids setting the global static ppapi_globals_. For unit
   // tests that use this feature, the "test" PpapiGlobals should be constructed
   // using this method. See SetPpapiGlobalsOnThreadForTest for more information.
   struct ForTest {};
-  PpapiGlobals(ForTest);
+  explicit PpapiGlobals(ForTest);
 
   virtual ~PpapiGlobals();
 
   // Getter for the global singleton.
   inline static PpapiGlobals* Get() {
     if (ppapi_globals_)
       return ppapi_globals_;
     // In unit tests, the following might be valid (see
     // SetPpapiGlobalsOnThreadForTest). Normally, this will just return NULL.
     return GetThreadLocalPointer();
   }
 
   // This allows us to set a given PpapiGlobals object as the PpapiGlobals for
   // a given thread. After setting the PpapiGlobals for a thread, Get() will
   // return that PpapiGlobals when Get() is called on that thread. Other threads
   // are unaffected. This allows us to have tests which use >1 PpapiGlobals in
   // the same process, e.g. for having 1 thread emulate the "host" and 1 thread
   // emulate the "plugin".
   //
   // PpapiGlobals object must have been constructed using the "ForTest"
   // parameter.
   static void SetPpapiGlobalsOnThreadForTest(PpapiGlobals* ptr);
 
   // Retrieves the corresponding tracker.
   virtual ResourceTracker* GetResourceTracker() = 0;
   virtual VarTracker* GetVarTracker() = 0;
   virtual CallbackTracker* GetCallbackTrackerForInstance(
       PP_Instance instance) = 0;
+
   virtual base::Lock* GetProxyLock() = 0;
 
   // Logs the given string to the JS console. If "source" is empty, the name of
   // the current module will be used, if it can be determined.
   virtual void LogWithSource(PP_Instance instance,
                              PP_LogLevel_Dev level,
                              const std::string& source,
                              const std::string& value) = 0;
 
   // Like LogWithSource but broadcasts the log to all instances of the given
@@ skipping 12 matching lines @@
   // Returns the given API object associated with the given instance, or NULL
   // if the instance is invalid.
   virtual thunk::PPB_Instance_API* GetInstanceAPI(PP_Instance instance) = 0;
   virtual thunk::ResourceCreationAPI* GetResourceCreationAPI(
       PP_Instance instance) = 0;
 
   // Returns the PP_Module associated with the given PP_Instance, or 0 on
   // failure.
   virtual PP_Module GetModuleForInstance(PP_Instance instance) = 0;
 
-  // Returns the base::MessageLoopProxy for the main thread. Note that this must
-  // be called on the main thread the first time so that it can initialize
-  // its static data.
+  // Returns the base::MessageLoopProxy for the main thread. This is set in the
+  // constructor, so PpapiGlobals must be created on the main thread.
   base::MessageLoopProxy* GetMainThreadMessageLoop();
 
+  // Return the MessageLoopShared of the current thread, if any. This will
+  // always return NULL on the host side, where PPB_MessageLoop is not
+  // supported.
+  virtual MessageLoopShared* GetCurrentMessageLoop() = 0;
+
   // Returns the command line for the process.
   virtual std::string GetCmdLine() = 0;
 
   // Preloads the font on Windows, does nothing on other platforms.
   // TODO(brettw) remove this by passing the instance into the API so we don't
   // have to have it on the globals.
   virtual void PreCacheFontForFlash(const void* logfontw) = 0;
 
   virtual bool IsHostGlobals() const;
   virtual bool IsPluginGlobals() const;
 
  private:
   // Return the thread-local pointer which is used only for unit testing. It
   // should always be NULL when running in production. It allows separate
   // threads to have distinct "globals".
   static PpapiGlobals* GetThreadLocalPointer();
 
   static PpapiGlobals* ppapi_globals_;
 
-  scoped_refptr<base::MessageLoopProxy> message_loop_proxy_;
+  scoped_refptr<base::MessageLoopProxy> main_loop_proxy_;
 
   DISALLOW_COPY_AND_ASSIGN(PpapiGlobals);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_PPAPI_GLOBALS_H_