Prevent DCHECK on shutdown of EmbeddedApplicationRunner

content/common/mojo/embedded_application_runner.cc

 // 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.
 
 #include "content/common/mojo/embedded_application_runner.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/macros.h"
@@ skipping 34 matching lines @@
 
     DCHECK(application_task_runner_);
     application_task_runner_->PostTask(
         FROM_HERE,
         base::Bind(&Instance::BindServiceRequestOnApplicationThread, this,
                    base::Passed(&request)));
   }
 
   void ShutDown() {
     DCHECK(runner_thread_checker_.CalledOnValidThread());
-    if (thread_) {
-      thread_.reset();
-      application_task_runner_ = nullptr;
+    if (!application_task_runner_)
+      return;
+    // Any extant ServiceContexts must be destroyed on the application thread.
+    if (application_task_runner_->BelongsToCurrentThread()) {
+      Quit();
+    } else {
+      application_task_runner_->PostTask(FROM_HERE,
+                                         base::Bind(&Instance::Quit, this));
     }
   }
 
  private:
+  friend class base::RefCountedThreadSafe<Instance>;
+
+  ~Instance() {
+    // If this instance had its own thread, it MUST be explicitly destroyed by
+    // QuitOnRunnerThread() by the time this destructor is run.
+    DCHECK(!thread_);
+  }
+
   void BindServiceRequestOnApplicationThread(
       shell::mojom::ServiceRequest request) {
     DCHECK(application_task_runner_->BelongsToCurrentThread());
 
     if (!service_) {
       service_ = factory_callback_.Run(
           base::Bind(&Instance::Quit, base::Unretained(this)));
     }
 
     shell::ServiceContext* new_connection =
         new shell::ServiceContext(service_.get(), std::move(request));
     shell_connections_.push_back(base::WrapUnique(new_connection));
     new_connection->SetConnectionLostClosure(
         base::Bind(&Instance::OnStop, base::Unretained(this),
                    new_connection));
   }
 
- private:
-  friend class base::RefCountedThreadSafe<Instance>;
-
-  ~Instance() {
-    // If this instance had its own thread, it MUST be explicitly destroyed by
-    // ShutDown() on the runner's thread by the time this destructor is run.
-    DCHECK(!thread_);
-  }
-
   void OnStop(shell::ServiceContext* connection) {
     DCHECK(application_task_runner_->BelongsToCurrentThread());
 
     for (auto it = shell_connections_.begin(); it != shell_connections_.end();
          ++it) {
       if (it->get() == connection) {
         shell_connections_.erase(it);
         break;
       }
     }
   }
 
   void Quit() {
     DCHECK(application_task_runner_->BelongsToCurrentThread());
 
     shell_connections_.clear();
     service_.reset();
-    quit_task_runner_->PostTask(
-        FROM_HERE, base::Bind(&Instance::QuitOnRunnerThread, this));
+    if (quit_task_runner_->BelongsToCurrentThread()) {
+      QuitOnRunnerThread();
+    } else {
+      quit_task_runner_->PostTask(
+          FROM_HERE, base::Bind(&Instance::QuitOnRunnerThread, this));
+    }
   }
 
   void QuitOnRunnerThread() {
     DCHECK(runner_thread_checker_.CalledOnValidThread());
-    ShutDown();
+    if (thread_) {
+      thread_.reset();
+      application_task_runner_ = nullptr;
+    }
     quit_closure_.Run();
   }
 
   const std::string name_;
   const MojoApplicationInfo::ApplicationFactory factory_callback_;
   const bool use_own_thread_;
   const base::Closure quit_closure_;
   const scoped_refptr<base::SingleThreadTaskRunner> quit_task_runner_;
 
   // Thread checker used to ensure certain operations happen only on the
@@ skipping 35 matching lines @@
     const base::Closure& quit_closure) {
   quit_closure_ = quit_closure;
 }
 
 void EmbeddedApplicationRunner::OnQuit() {
   if (!quit_closure_.is_null())
     quit_closure_.Run();
 }
 
 }  // namespace content