Prevent DCHECK on shutdown of EmbeddedApplicationRunner

content/common/mojo/embedded_application_runner.cc

Index: content/common/mojo/embedded_application_runner.cc
diff --git a/content/common/mojo/embedded_application_runner.cc b/content/common/mojo/embedded_application_runner.cc
index 5d7abed900d54549082faca86bd848afaba85048..e28fbfc94b28d54db1b492ca46ed957d621f40a5 100644
--- a/content/common/mojo/embedded_application_runner.cc
+++ b/content/common/mojo/embedded_application_runner.cc
@@ -52,6 +52,11 @@ class EmbeddedApplicationRunner::Instance
 
   void ShutDown() {
     DCHECK(runner_thread_checker_.CalledOnValidThread());
+    // Any extant ServiceContexts must be destroyed on the correct thread.

[Ken Rockot(use gerrit already), 2016/07/27 18:23:05]

If application_task_runner_ is null, the app has already been torn down and
there's nothing to do.
So I would change this to


if (!application_task_runner_)
  return;
if (application_task_runner_->BelongsToCurrentThread())
  Quit();
else
  // the PostTask you're adding here

[kmackay, 2016/07/27 18:51:59]

Done.

+    if (application_task_runner_) {
+      application_task_runner_->PostTask(FROM_HERE,
+                                         base::Bind(&Instance::Quit, this));
+    }
     if (thread_) {

[Ken Rockot(use gerrit already), 2016/07/27 18:23:05]

And you can just delete this block now

[kmackay, 2016/07/27 18:51:59]

I wasn't sure if we wanted to make sure that the application thread was dead
before completing the destruction of EmbeddedApplicationRunner. I guess it must
be safe though since it needs to work when use_own_thread_ is false.

       thread_.reset();
       application_task_runner_ = nullptr;
@@ -108,7 +113,10 @@ class EmbeddedApplicationRunner::Instance
 
   void QuitOnRunnerThread() {
     DCHECK(runner_thread_checker_.CalledOnValidThread());
-    ShutDown();
+    if (thread_) {
+      thread_.reset();
+      application_task_runner_ = nullptr;
+    }
     quit_closure_.Run();
   }