Add REAL_TASK_SCHEDULER option in TestBrowserThreadBundle.

content/public/test/test_browser_thread_bundle.cc

Index: content/public/test/test_browser_thread_bundle.cc
diff --git a/content/public/test/test_browser_thread_bundle.cc b/content/public/test/test_browser_thread_bundle.cc
index a7fdd7602757462d7d6ec8245224ee7b84f4e93a..402ccb368d17dcf418df41a2dab5d31fb7d9fa17 100644
--- a/content/public/test/test_browser_thread_bundle.cc
+++ b/content/public/test/test_browser_thread_bundle.cc
@@ -7,6 +7,7 @@
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
+#include "base/test/scoped_async_task_scheduler.h"
 #include "base/test/scoped_task_scheduler.h"
 #include "content/browser/browser_thread_impl.h"
 #include "content/public/test/test_browser_thread.h"
@@ -55,7 +56,8 @@ TestBrowserThreadBundle::~TestBrowserThreadBundle() {
   ui_thread_->Stop();
   base::RunLoop().RunUntilIdle();
 
-  task_scheduler_.reset();
+  scoped_async_task_scheduler_.reset();
+  scoped_task_scheduler_.reset();
 
   // |message_loop_| needs to explicitly go away before fake threads in order
   // for DestructionObservers hooked to |message_loop_| to be able to invoke
@@ -86,8 +88,13 @@ void TestBrowserThreadBundle::Init() {
 void TestBrowserThreadBundle::CreateThreads() {
   DCHECK(!threads_created_);
 
-  task_scheduler_.reset(
-      new base::test::ScopedTaskScheduler(message_loop_.get()));
+  if (options_ & REAL_TASK_SCHEDULER) {
+    scoped_async_task_scheduler_.reset(
+        new base::test::ScopedAsyncTaskScheduler());

[robliao, 2017/01/12 20:15:02]

Should Async instead have been an option off of ScopedTaskScheduler?

[fdoray, 2017/01/12 21:25:56]

No. It is very convenient to be able to add a ScopedAsyncTaskScheduler member to
a test fixture instead of a ScopedTaskScheduler member + initialization with a
custom flag in the constructor. It is also easier to find ScopedTaskScheduler
vs. ScopedAsyncTaskSchedulers in code search with different class names.

[robliao, 2017/01/12 21:31:03]

Do we expect many uses of ScopedAsyncTaskScheduler? My reading is that we want
folks to use ScopedTaskScheduler and only used ScopedAsyncTaskScheduler
sparingly.

If that's the case, there are likely going to be very few users of this, so I
would be fine with those folks going through the extra hoop of initializing the
member with the async option in their constructor.

Search should be easy as we can look for the use of the option.

+  } else {
+    scoped_task_scheduler_.reset(
+        new base::test::ScopedTaskScheduler(message_loop_.get()));
+  }
 
   if (options_ & REAL_DB_THREAD) {
     db_thread_.reset(new TestBrowserThread(BrowserThread::DB));