Fix flaky linux panel tests related to active state checks

chrome/browser/ui/panels/test_panel_active_state_observer.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 "chrome/browser/ui/panels/test_panel_active_state_observer.h"
+
+#include "chrome/browser/ui/panels/panel.h"
+#include "chrome/common/chrome_notification_types.h"
+
+PanelActiveStateObserver::PanelActiveStateObserver(
+    Panel* panel,
+    bool expect_active)
+    : panel_(panel),
+      expect_active_(expect_active),
+      seen_(false),
+      running_(false) {
+  registrar_.Add(this, chrome::NOTIFICATION_PANEL_CHANGED_ACTIVE_STATUS,
+                 content::Source<Panel>(panel));
+}
+
+PanelActiveStateObserver::~PanelActiveStateObserver() {}
+
+void PanelActiveStateObserver::Wait() {
+  if (seen_ || AtExpectedState())
+    return;
+
+  running_ = true;
+  message_loop_runner_ = new ui_test_utils::MessageLoopRunner;
+  message_loop_runner_->Run();
+  EXPECT_TRUE(seen_);
+}
+
+bool PanelActiveStateObserver::AtExpectedState() {
+  return panel_->IsActive() == expect_active_;
+}
+
+void PanelActiveStateObserver::Observe(
+    int type,
+    const content::NotificationSource& source,
+    const content::NotificationDetails& details) {
+  if (!running_)
+    return;
+
+  if (AtExpectedState()) {
+    seen_ = true;
+    message_loop_runner_->Quit();
+    running_ = false;
+  }
+}