Implement a poor man's PostAfterStartupTask() function.

chrome/browser/after_startup_task_utils_unittest.cc

Index: chrome/browser/after_startup_task_utils_unittest.cc
diff --git a/chrome/browser/after_startup_task_utils_unittest.cc b/chrome/browser/after_startup_task_utils_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0b449f7054d298979c4cecbe4df2ec2aa0d0a0eb
--- /dev/null
+++ b/chrome/browser/after_startup_task_utils_unittest.cc
@@ -0,0 +1,188 @@
+// Copyright 2015 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 "chrome/browser/after_startup_task_utils.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop/message_loop.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/run_loop.h"
+#include "base/task_runner_util.h"
+#include "base/threading/thread.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/test/test_browser_thread_bundle.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using base::RunLoop;
+using content::BrowserThread;
+using content::TestBrowserThreadBundle;
+
+namespace {
+
+class WrappedTaskRunner : public base::TaskRunner {
+ public:
+  explicit WrappedTaskRunner(const scoped_refptr<TaskRunner>& real_runner)
+      : real_task_runner_(real_runner),
+        posted_task_count_(0),

[cmumford, 2015/04/06 23:18:03]

Nit: Use Non-Static Class Member Initializers

[michaeln, 2015/04/06 23:45:59]

Done

+        ran_task_count_(0) {}
+
+  bool PostDelayedTask(const tracked_objects::Location& from_here,
+                       const base::Closure& task,
+                       base::TimeDelta delay) override {
+    ++posted_task_count_;
+    return real_task_runner_->PostDelayedTask(
+        from_here, base::Bind(&WrappedTaskRunner::RunWrappedTask, this, task),
+        base::TimeDelta());  // Squash all delays so our tests complete asap.
+  }
+
+  bool RunsTasksOnCurrentThread() const override {
+    return real_task_runner_->RunsTasksOnCurrentThread();
+  }
+
+  base::TaskRunner* real_runner() const { return real_task_runner_.get(); }
+
+  int total_task_count() const { return posted_task_count_ + ran_task_count_; }
+  int posted_task_count() const { return posted_task_count_; }
+  int ran_task_count() const { return ran_task_count_; }
+
+  void reset_task_counts() {
+    posted_task_count_ = 0;
+    ran_task_count_ = 0;
+  }
+
+ private:
+  void RunWrappedTask(const base::Closure& task) {
+    ++ran_task_count_;
+    task.Run();
+  }
+
+  scoped_refptr<TaskRunner> real_task_runner_;
+  int posted_task_count_;
+  int ran_task_count_;
+};
+
+}  // namespace
+
+class AfterStartupTaskTest : public testing::Test {
+ public:
+  AfterStartupTaskTest()
+      : browser_thread_bundle_(TestBrowserThreadBundle::REAL_DB_THREAD) {
+    ui_thread_ = new WrappedTaskRunner(
+        BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI));
+
+    db_thread_ = new WrappedTaskRunner(
+        BrowserThread::GetMessageLoopProxyForThread(BrowserThread::DB));
+    AfterStartupTaskUtils::UnsafeReset();
+  }
+
+  // Hop to the db thread and call IsBrowserStartupComplete.
+  bool GetIsBrowserStartupCompleteFromDBThread() {
+    RunLoop run_loop;
+    bool is_complete;
+    base::PostTaskAndReplyWithResult(
+        db_thread_->real_runner(), FROM_HERE,
+        base::Bind(&AfterStartupTaskUtils::IsBrowserStartupComplete),
+        base::Bind(&AfterStartupTaskTest::GotIsOnBrowserStartupComplete,
+                   &run_loop, &is_complete));
+    run_loop.Run();
+    return is_complete;
+  }
+
+  // Hop to the db thread and call PostAfterStartupTask.
+  void PostAfterStartupTaskFromDBThread(
+      const tracked_objects::Location& from_here,
+      const scoped_refptr<base::TaskRunner>& task_runner,
+      const base::Closure& task) {
+    RunLoop run_loop;
+    db_thread_->real_runner()->PostTaskAndReply(
+        FROM_HERE, base::Bind(&AfterStartupTaskUtils::PostTask, from_here,
+                              task_runner, task),
+        base::Bind(&RunLoop::Quit, base::Unretained(&run_loop)));
+    run_loop.Run();
+  }
+
+  // Make sure all tasks posted to the DB thread get run.
+  void FlushDBThread() {
+    RunLoop run_loop;
+    db_thread_->real_runner()->PostTaskAndReply(
+        FROM_HERE, base::Bind(&base::DoNothing),
+        base::Bind(&RunLoop::Quit, base::Unretained(&run_loop)));
+    run_loop.Run();
+  }
+
+ protected:
+  scoped_refptr<WrappedTaskRunner> ui_thread_;
+  scoped_refptr<WrappedTaskRunner> db_thread_;
+
+ private:
+  static void GotIsOnBrowserStartupComplete(RunLoop* loop,
+                                            bool* out,
+                                            bool is_complete) {
+    *out = is_complete;
+    loop->Quit();
+  }
+
+  TestBrowserThreadBundle browser_thread_bundle_;
+};
+
+TEST_F(AfterStartupTaskTest, IsStartupComplete) {
+  // Check IsBrowserStartupComplete on a background thread first to
+  // verify that it does not allocate the underlying flag on that thread.
+  EXPECT_FALSE(GetIsBrowserStartupCompleteFromDBThread());
+  EXPECT_FALSE(AfterStartupTaskUtils::IsBrowserStartupComplete());
+  AfterStartupTaskUtils::SetBrowserStartupIsComplete();

[cmumford, 2015/04/06 23:18:03]

Can you add a comment explaining this test relies on a DCHECK in the impl?

[michaeln, 2015/04/06 23:45:59]

Done.

+  EXPECT_TRUE(AfterStartupTaskUtils::IsBrowserStartupComplete());
+  EXPECT_TRUE(GetIsBrowserStartupCompleteFromDBThread());
+}
+
+TEST_F(AfterStartupTaskTest, PostTask) {
+  // Nothing should be posted prior to startup completion.
+  EXPECT_FALSE(AfterStartupTaskUtils::IsBrowserStartupComplete());
+  AfterStartupTaskUtils::PostTask(FROM_HERE, ui_thread_,
+                                  base::Bind(&base::DoNothing));
+  AfterStartupTaskUtils::PostTask(FROM_HERE, db_thread_,
+                                  base::Bind(&base::DoNothing));
+  PostAfterStartupTaskFromDBThread(FROM_HERE, ui_thread_,
+                                   base::Bind(&base::DoNothing));
+  PostAfterStartupTaskFromDBThread(FROM_HERE, db_thread_,
+                                   base::Bind(&base::DoNothing));
+  FlushDBThread();
+  RunLoop().RunUntilIdle();
+  EXPECT_EQ(0, db_thread_->total_task_count());
+  EXPECT_EQ(0, ui_thread_->total_task_count());
+
+  // Queued tasks should be posted upon setting the flag.
+  AfterStartupTaskUtils::SetBrowserStartupIsComplete();
+  EXPECT_EQ(2, db_thread_->posted_task_count());
+  EXPECT_EQ(2, ui_thread_->posted_task_count());
+  FlushDBThread();
+  RunLoop().RunUntilIdle();
+  EXPECT_EQ(2, db_thread_->ran_task_count());
+  EXPECT_EQ(2, ui_thread_->ran_task_count());
+
+  db_thread_->reset_task_counts();
+  ui_thread_->reset_task_counts();

[cmumford, 2015/04/06 23:18:03]

What do you think about maybe resetting only one of them? Might catch more
errors.

[michaeln, 2015/04/06 23:45:58]

Instead, I made some of the tasks verify they're running on the right thread.

+
+  // Tasks posted after startup should get posted immediately.

[cmumford, 2015/04/06 23:18:03]

Do you want to add EXPECT_EQ(0, db_thread_->total_task_count()), ... just to be
on the safe side here?

[michaeln, 2015/04/06 23:45:58]

Done.

+  AfterStartupTaskUtils::PostTask(FROM_HERE, ui_thread_,
+                                  base::Bind(&base::DoNothing));
+  AfterStartupTaskUtils::PostTask(FROM_HERE, db_thread_,
+                                  base::Bind(&base::DoNothing));
+  EXPECT_EQ(1, db_thread_->posted_task_count());
+  EXPECT_EQ(1, ui_thread_->posted_task_count());
+  PostAfterStartupTaskFromDBThread(FROM_HERE, ui_thread_,
+                                   base::Bind(&base::DoNothing));
+  PostAfterStartupTaskFromDBThread(FROM_HERE, db_thread_,
+                                   base::Bind(&base::DoNothing));
+  FlushDBThread();
+  EXPECT_EQ(2, db_thread_->posted_task_count());
+  EXPECT_EQ(2, ui_thread_->posted_task_count());
+  FlushDBThread();
+  RunLoop().RunUntilIdle();
+  EXPECT_EQ(2, db_thread_->ran_task_count());
+  EXPECT_EQ(2, ui_thread_->ran_task_count());
+}