Add base::RunLoop and update ui_test_utils to use it to reduce flakiness

base/run_loop.cc

+// Copyright (c) 2012 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 "base/run_loop.h"
+
+#include "base/bind.h"
+
+namespace base {
+
+RunLoop::RunLoop()
+    : loop_(MessageLoop::current()),
+      run_called_(false),
+      quit_called_(false),
+      running_(false),
+      run_depth_(0),
+      quit_when_idle_received_(false) {
+#if !defined(OS_MACOSX) && !defined(OS_ANDROID)
+   dispatcher_ = NULL;
+#endif
+}
+
+#if !defined(OS_MACOSX) && !defined(OS_ANDROID)
+RunLoop::RunLoop(MessageLoop::Dispatcher* dispatcher)
+    : loop_(MessageLoop::current()),
+      run_called_(false),
+      quit_called_(false),
+      running_(false),
+      run_depth_(0),
+      quit_when_idle_received_(false),
+      dispatcher_(dispatcher) {
+}
+#endif
+
+RunLoop::~RunLoop() {
+}
+
+void RunLoop::Run() {
+  if (!BeforeRun())
+    return;
+  loop_->RunHandler();
+  AfterRun();
+}
+
+void RunLoop::RunUntilIdle() {
+  quit_when_idle_received_ = true;
+  Run();
+}
+
+void RunLoop::Quit() {
+  quit_called_ = true;
+  if (running_ && loop_->run_loop_ == this) {
+    // This is the inner-most RunLoop, so quit now.
+    loop_->QuitNow();
+  }
+}
+
+base::Closure RunLoop::QuitClosure() {
+  return base::Bind(&RunLoop::Quit, AsWeakPtr());
+}
+
+bool RunLoop::BeforeRun() {
+  DCHECK(!run_called_);
+  run_called_ = true;
+
+  // Allow Quit to be called before Run.
+  if (quit_called_)
+    return false;
+
+  // Push RunLoop stack:
+  previous_run_loop_ = loop_->run_loop_;
+  run_depth_ = previous_run_loop_? previous_run_loop_->run_depth_ + 1 : 1;
+  loop_->run_loop_ = AsWeakPtr();
+
+  running_ = true;
+  return true;
+}
+
+void RunLoop::AfterRun() {
+  running_ = false;
+
+  // Pop RunLoop stack:
+  loop_->run_loop_ = previous_run_loop_;
+
+  // Execute deferred QuitNow, if any:
+  if (previous_run_loop_ && previous_run_loop_->quit_called_)
+    loop_->QuitNow();
+}
+
+}  // namespace base