Change DONT_START_THREADS to DONT_CREATE_THREADS in TestBrowserThreadBundle.

In a real browser process, threads are started as BrowserThreadImpl
objects are created. TestBrowserThreadBundle should do the same.

This is a pre-requisite to add the option to create a real TaskScheduler
in TestBrowserThreadBundle, because TaskScheduler has to be created and
started at the same time.

BUG=659191

Review-Url: https://codereview.chromium.org/2628903002
Cr-Commit-Position: refs/heads/master@{#443536}

chrome/browser/io_thread_unittest.cc

@@ -107,7 +107,7 @@ class IOThreadTestWithIOThreadObject : public testing::Test {
  protected:
   IOThreadTestWithIOThreadObject()
       : thread_bundle_(content::TestBrowserThreadBundle::REAL_IO_THREAD |
-                       content::TestBrowserThreadBundle::DONT_START_THREADS) {
+                       content::TestBrowserThreadBundle::DONT_CREATE_THREADS) {
 #if BUILDFLAG(ENABLE_EXTENSIONS)
     event_router_forwarder_ = new extensions::EventRouterForwarder;
 #endif
@@ -139,7 +139,7 @@ class IOThreadTestWithIOThreadObject : public testing::Test {
     // Now that IOThread object is registered starting the threads will
     // call the IOThread::Init(). This sets up the environment needed for
     // these tests.
-    thread_bundle_.Start();
+    thread_bundle_.CreateThreads();
   }
 
   ~IOThreadTestWithIOThreadObject() override {

content/public/test/test_browser_thread_bundle.cc

@@ -17,11 +17,13 @@ TestBrowserThreadBundle::TestBrowserThreadBundle()
     : TestBrowserThreadBundle(DEFAULT) {}
 
 TestBrowserThreadBundle::TestBrowserThreadBundle(int options)
-    : options_(options), threads_started_(false) {
+    : options_(options), threads_created_(false) {
   Init();
 }
 
 TestBrowserThreadBundle::~TestBrowserThreadBundle() {
+  DCHECK(threads_created_);
+
   // To avoid memory leaks, we must ensure that any tasks posted to the blocking
   // pool via PostTaskAndReply are able to reply back to the originating thread.
   // Thus we must flush the blocking pool while the browser threads still exist.
@@ -65,23 +67,34 @@ TestBrowserThreadBundle::~TestBrowserThreadBundle() {
 void TestBrowserThreadBundle::Init() {
   // Check for conflicting options can't have two IO threads.
   CHECK(!(options_ & IO_MAINLOOP) || !(options_ & REAL_IO_THREAD));
-  // There must be a thread to start to use DONT_START_THREADS
-  CHECK((options_ & ~IO_MAINLOOP) != DONT_START_THREADS);
+  // There must be a thread to start to use DONT_CREATE_THREADS
+  CHECK((options_ & ~IO_MAINLOOP) != DONT_CREATE_THREADS);
 
+  // Create the UI thread. In production, this work is done in
+  // BrowserMainLoop::MainMessageLoopStart().
   if (options_ & IO_MAINLOOP) {
     message_loop_.reset(new base::MessageLoopForIO());
   } else {
     message_loop_.reset(new base::MessageLoopForUI());
   }
 
-  task_scheduler_.reset(
-      new base::test::ScopedTaskScheduler(message_loop_.get()));
-
   ui_thread_.reset(
       new TestBrowserThread(BrowserThread::UI, message_loop_.get()));
 
+  if (!(options_ & DONT_CREATE_THREADS))
+    CreateThreads();
+}
+
+// This method mimics the work done in BrowserMainLoop::CreateThreads().
+void TestBrowserThreadBundle::CreateThreads() {
+  DCHECK(!threads_created_);
+
+  task_scheduler_.reset(
+      new base::test::ScopedTaskScheduler(message_loop_.get()));
+
   if (options_ & REAL_DB_THREAD) {
     db_thread_.reset(new TestBrowserThread(BrowserThread::DB));
+    db_thread_->Start();
   } else {
     db_thread_.reset(
         new TestBrowserThread(BrowserThread::DB, message_loop_.get()));
@@ -89,6 +102,7 @@ void TestBrowserThreadBundle::Init() {
 
   if (options_ & REAL_FILE_THREAD) {
     file_thread_.reset(new TestBrowserThread(BrowserThread::FILE));
+    file_thread_->Start();
   } else {
     file_thread_.reset(
         new TestBrowserThread(BrowserThread::FILE, message_loop_.get()));
@@ -103,28 +117,13 @@ void TestBrowserThreadBundle::Init() {
 
   if (options_ & REAL_IO_THREAD) {
     io_thread_.reset(new TestBrowserThread(BrowserThread::IO));
+    io_thread_->StartIOThread();
   } else {
     io_thread_.reset(
         new TestBrowserThread(BrowserThread::IO, message_loop_.get()));
   }
 
-  if (!(options_ & DONT_START_THREADS))
-    Start();
-}
-
-void TestBrowserThreadBundle::Start() {
-  DCHECK(!threads_started_);
-
-  if (options_ & REAL_DB_THREAD)
-    db_thread_->Start();
-
-  if (options_ & REAL_FILE_THREAD)
-    file_thread_->Start();
-
-  if (options_ & REAL_IO_THREAD)
-    io_thread_->StartIOThread();
-
-  threads_started_ = true;
+  threads_created_ = true;
 }
 
 }  // namespace content

content/public/test/test_browser_thread_bundle.h

@@ -26,13 +26,11 @@
 // REAL_IO_THREAD.
 //
 // For some tests it is important to emulate real browser startup. During real
-// browser startup some initialization is done (e.g. creation of thread objects)
-// between creating the main thread message loop, which is bound to the existing
-// main thread, and starting the other threads. Passing DONT_START_THREADS to
-// constructor will delay staring these other threads until the test explicitly
-// calls Start().
+// browser startup, the main MessageLoop is created before other threads.
+// Passing DONT_CREATE_THREADS to constructor will delay creating other threads
+// until the test explicitly calls CreateThreads().
 //
-// DONT_START_THREADS should only be used when the options specify at least
+// DONT_CREATE_THREADS should only be used when the options specify at least
 // one real thread other than the main thread.
 
 #ifndef CONTENT_PUBLIC_TEST_TEST_BROWSER_THREAD_BUNDLE_H_
@@ -64,15 +62,15 @@ class TestBrowserThreadBundle {
     REAL_DB_THREAD = 0x02,
     REAL_FILE_THREAD = 0x08,
     REAL_IO_THREAD = 0x10,
-    DONT_START_THREADS = 0x20,
+    DONT_CREATE_THREADS = 0x20,
   };
 
   TestBrowserThreadBundle();
   explicit TestBrowserThreadBundle(int options);
 
-  // Start the real threads; should only be called from other classes if the
-  // DONT_START_THREADS option was used when the bundle was created.
-  void Start();
+  // Creates threads; should only be called from other classes if the
+  // DONT_CREATE_THREADS option was used when the bundle was created.
+  void CreateThreads();
 
   ~TestBrowserThreadBundle();
 
@@ -90,7 +88,7 @@ class TestBrowserThreadBundle {
   std::unique_ptr<TestBrowserThread> io_thread_;
 
   int options_;
-  bool threads_started_;
+  bool threads_created_;
 
   DISALLOW_COPY_AND_ASSIGN(TestBrowserThreadBundle);
 };