cros: Suspend media sessions with display off trigger by tablet power button

chrome/browser/ui/ash/chrome_shell_delegate.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/ash/chrome_shell_delegate.h"
 
 #include <stddef.h>
 
 #include <limits>
 
@@ skipping 42 matching lines @@
 #include "chrome/browser/ui/ash/system_tray_delegate_chromeos.h"
 #include "chrome/browser/ui/aura/accessibility/automation_manager_aura.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_commands.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_navigator.h"
 #include "chrome/browser/ui/browser_navigator_params.h"
 #include "chrome/browser/ui/browser_tabstrip.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/scoped_tabbed_browser_displayer.h"
+#include "chrome/browser/ui/tab_contents/tab_contents_iterator.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/grit/chromium_strings.h"
 #include "chrome/grit/generated_resources.h"
 #include "chrome/grit/theme_resources.h"
 #include "chromeos/chromeos_switches.h"
 #include "components/prefs/pref_service.h"
 #include "components/user_manager/user.h"
 #include "components/user_manager/user_manager.h"
+#include "content/public/browser/media_session.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/common/service_manager_connection.h"
 #include "ui/aura/window.h"
 #include "ui/base/ime/chromeos/input_method_manager.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
 
 using chromeos::AccessibilityManager;
 
 namespace {
@@ skipping 502 matching lines @@
 
 void ChromeShellDelegate::UpdateTouchscreenStatusFromPrefs() {
   chromeos::system::InputDeviceSettings::Get()
       ->UpdateTouchscreenStatusFromPrefs();
 }
 
 void ChromeShellDelegate::ToggleTouchpad() {
   chromeos::system::InputDeviceSettings::Get()->ToggleTouchpad();
 }
 
+void ChromeShellDelegate::ResumeMediaSessions() {
+  for (TabContentsIterator it; !it.done(); it.Next()) {
+    content::MediaSession::Get(*it)->Resume(
+        content::MediaSession::SuspendType::SYSTEM);

[Daniel Erat, 2017/05/17 01:22:25]

is SYSTEM actually an appropriate type to use here? from looking at the
comments, UI seems like it might be better.

  enum class SuspendType {
    // Suspended by the system because a transient sound needs to be played.
    SYSTEM,
    // Suspended by the UI.
    UI,
    // Suspended by the page via script or user interaction.
    CONTENT,
  };

[mlamouri (slow - plz ping), 2017/05/17 12:52:26]

System sounds like the right thing to do here. The comments, as with all
documentation, are slightly outdated and are focused on Chrome Android. In CrOS
case, it's fair to say that the behaviour you have is part of the system.

Note that it shouldn't matter much apart that suspend/resume should use the same
ID and UMAs will vary.

[Qiang(Joe) Xu, 2017/05/22 22:58:47]

mlamouri@, since we are not actually entering suspended state for power button
pressed, it is just a screen brightness off with chrome still running, is SYSTEM
still preferred over UI?

+  }
+}
+
+void ChromeShellDelegate::SuspendMediaSessions() {
+  for (TabContentsIterator it; !it.done(); it.Next()) {
+    content::MediaSession::Get(*it)->Suspend(
+        content::MediaSession::SuspendType::SYSTEM);
+  }
+}
+
 keyboard::KeyboardUI* ChromeShellDelegate::CreateKeyboardUI() {
   return new ChromeKeyboardUI(ProfileManager::GetActiveUserProfile());
 }
 
 ash::SessionStateDelegate* ChromeShellDelegate::CreateSessionStateDelegate() {
   return new SessionStateDelegateChromeos;
 }
 
 ash::AccessibilityDelegate* ChromeShellDelegate::CreateAccessibilityDelegate() {
   return new AccessibilityDelegateImpl;
@@ skipping 42 matching lines @@
       NOTREACHED() << "Unexpected notification " << type;
   }
 }
 
 void ChromeShellDelegate::PlatformInit() {
   registrar_.Add(this, chrome::NOTIFICATION_LOGIN_USER_PROFILE_PREPARED,
                  content::NotificationService::AllSources());
   registrar_.Add(this, chrome::NOTIFICATION_SESSION_STARTED,
                  content::NotificationService::AllSources());
 }