Fix hangs in Mandoline page cycler on Linux with --enable-multiprocess.

mojo/application/public/cpp/lib/content_handler_factory.cc

 // Copyright 2014 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.
 
 #include "mojo/application/public/cpp/content_handler_factory.h"
 
 #include <set>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 13 matching lines @@
 
 namespace {
 
 class ApplicationThread : public base::PlatformThread::Delegate {
  public:
   ApplicationThread(
       scoped_refptr<base::SingleThreadTaskRunner> handler_thread,
       const base::Callback<void(ApplicationThread*)>& termination_callback,
       ContentHandlerFactory::Delegate* handler_delegate,
       InterfaceRequest<Application> application_request,
-      URLResponsePtr response)
+      URLResponsePtr response,
+      const Callback<void()>& destruct_callback)
       : handler_thread_(handler_thread),
         termination_callback_(termination_callback),
         handler_delegate_(handler_delegate),
         application_request_(application_request.Pass()),
-        response_(response.Pass()) {}
+        response_(response.Pass()),
+        destruct_callback_(destruct_callback) {}
+
+  ~ApplicationThread() override {
+    destruct_callback_.Run();
+  }
 
  private:
   void ThreadMain() override {
     handler_delegate_->RunApplication(application_request_.Pass(),
                                       response_.Pass());
     handler_thread_->PostTask(FROM_HERE,
                               base::Bind(termination_callback_, this));
   }
 
   scoped_refptr<base::SingleThreadTaskRunner> handler_thread_;
   base::Callback<void(ApplicationThread*)> termination_callback_;
   ContentHandlerFactory::Delegate* handler_delegate_;
   InterfaceRequest<Application> application_request_;
   URLResponsePtr response_;
+  Callback<void()> destruct_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(ApplicationThread);
 };
 
 class ContentHandlerImpl : public ContentHandler {
  public:
   ContentHandlerImpl(ContentHandlerFactory::Delegate* delegate,
                      InterfaceRequest<ContentHandler> request)
       : delegate_(delegate),
         binding_(this, request.Pass()),
         weak_factory_(this) {}
   ~ContentHandlerImpl() override {
     // We're shutting down and doing cleanup. Cleanup may trigger calls back to
     // OnThreadEnd(). As we're doing the cleanup here we don't want to do it in
     // OnThreadEnd() as well. InvalidateWeakPtrs() ensures we don't get any
     // calls to OnThreadEnd().
     weak_factory_.InvalidateWeakPtrs();
     for (auto thread : active_threads_) {
       base::PlatformThread::Join(thread.second);
       delete thread.first;
     }
   }
 
  private:
   // Overridden from ContentHandler:
-  void StartApplication(InterfaceRequest<Application> application_request,
-                        URLResponsePtr response) override {
+  void StartApplication(
+      InterfaceRequest<Application> application_request,
+      URLResponsePtr response,
+      const Callback<void()>& destruct_callback) override {
     ApplicationThread* thread = new ApplicationThread(
         base::ThreadTaskRunnerHandle::Get(),
         base::Bind(&ContentHandlerImpl::OnThreadEnd,
                    weak_factory_.GetWeakPtr()),
-        delegate_, application_request.Pass(), response.Pass());
+        delegate_, application_request.Pass(), response.Pass(),
+        destruct_callback);
     base::PlatformThreadHandle handle;
     bool launched = base::PlatformThread::Create(0, thread, &handle);
     DCHECK(launched);
     active_threads_[thread] = handle;
   }
 
   void OnThreadEnd(ApplicationThread* thread) {
     DCHECK(active_threads_.find(thread) != active_threads_.end());
     base::PlatformThreadHandle handle = active_threads_[thread];
     active_threads_.erase(thread);
@@ skipping 27 matching lines @@
   if (application)
     loop.Run();
 }
 
 void ContentHandlerFactory::Create(ApplicationConnection* connection,
                                    InterfaceRequest<ContentHandler> request) {
   new ContentHandlerImpl(delegate_, request.Pass());
 }
 
 }  // namespace mojo