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

chrome/browser/ui/ash/chrome_shell_delegate.cc

Index: chrome/browser/ui/ash/chrome_shell_delegate.cc
diff --git a/chrome/browser/ui/ash/chrome_shell_delegate.cc b/chrome/browser/ui/ash/chrome_shell_delegate.cc
index b550ad2e967d17fd79e488c9f81b614caf89f402..bd98e2c1dd82d8748e03fa7f04eaa04a70c9f6ac 100644
--- a/chrome/browser/ui/ash/chrome_shell_delegate.cc
+++ b/chrome/browser/ui/ash/chrome_shell_delegate.cc
@@ -60,6 +60,7 @@
 #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"
@@ -68,6 +69,7 @@
 #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"
@@ -590,6 +592,20 @@ 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documentation, are slightly outdated and are focused on Chrome Android.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());
 }