Mojo C++ bindings: refactor SyncHandleWatcher.

mojo/public/cpp/bindings/lib/sync_handle_registry.h

 // Copyright 2016 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 MOJO_PUBLIC_CPP_BINDINGS_LIB_SYNC_HANDLE_WATCHER_H_
-#define MOJO_PUBLIC_CPP_BINDINGS_LIB_SYNC_HANDLE_WATCHER_H_
+#ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_SYNC_HANDLE_REGISTRY_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_LIB_SYNC_HANDLE_REGISTRY_H_
 
 #include <unordered_map>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/threading/thread_checker.h"
 #include "mojo/public/cpp/system/core.h"
 
 namespace mojo {
 namespace internal {
 
-// SyncHandleWatcher is used to support sync methods. While a sync call is
-// waiting for response, we would like incoming sync method requests on the same
-// thread to be able to reenter. We also would like master endpoints to continue
-// dispatching messages for associated endpoints on different threads.
-// Therefore, SyncHandleWatcher is used as thread-local storage to register all
-// handles that need to be watched while waiting for sync call responses.
+// SyncHandleRegistry is a thread-local storage to register handles that want to
+// be watched together.
 //
 // This class is not thread safe.
-class SyncHandleWatcher : public base::MessageLoop::DestructionObserver {
+class SyncHandleRegistry : public base::MessageLoop::DestructionObserver {
  public:
   // Returns a thread-local object.
-  static SyncHandleWatcher* current();
+  static SyncHandleRegistry* current();
 
   using HandleCallback = base::Callback<void(MojoResult)>;
   bool RegisterHandle(const Handle& handle,
                       MojoHandleSignals handle_signals,
                       const HandleCallback& callback);
 
   void UnregisterHandle(const Handle& handle);
 
   // Waits on all the registered handles and runs callbacks synchronously for
   // those ready handles.
   // The method:
   //   - returns true when any element of |should_stop| is set to true;
   //   - returns false when any error occurs.
   bool WatchAllHandles(const bool* should_stop[], size_t count);
 
  private:
   struct HandleHasher {
     size_t operator()(const Handle& handle) const {
       return std::hash<uint32_t>()(static_cast<uint32_t>(handle.value()));
     }
   };
   using HandleMap = std::unordered_map<Handle, HandleCallback, HandleHasher>;
 
-  SyncHandleWatcher();
-  ~SyncHandleWatcher() override;
+  SyncHandleRegistry();
+  ~SyncHandleRegistry() override;
 
   // base::MessageLoop::DestructionObserver implementation:
   void WillDestroyCurrentMessageLoop() override;
 
   HandleMap handles_;
 
   ScopedHandle wait_set_handle_;
 
+  scoped_refptr<base::RefCountedData<bool>> destroyed_;
+
   base::ThreadChecker thread_checker_;
 
-  DISALLOW_COPY_AND_ASSIGN(SyncHandleWatcher);
+  DISALLOW_COPY_AND_ASSIGN(SyncHandleRegistry);
 };
 
 }  // namespace internal
 }  // namespace mojo
 
-#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_SYNC_HANDLE_WATCHER_H_
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_SYNC_HANDLE_REGISTRY_H_