Disable background mode when associated pref changes.

BUG=53173
TEST=new BackgroundModeManager unit tests

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=57642

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=57749

Review URL: http://codereview.chromium.org/3205008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@57778 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 54 insertions, 13 deletions

diff --git a/chrome/browser/background_mode_manager.cc b/chrome/browser/background_mode_manager.cc
index 22060c0..263876a 100644
--- a/chrome/browser/background_mode_manager.cc
+++ b/chrome/browser/background_mode_manager.cc
@@ -42,15 +42,16 @@ const wchar_t* kBackgroundModeRegistrySubkey =
 const wchar_t* kBackgroundModeRegistryKeyName = L"chromium";
 #endif
 
-BackgroundModeManager::BackgroundModeManager(Profile* profile)
+BackgroundModeManager::BackgroundModeManager(Profile* profile,
+                                             CommandLine* command_line)
     : profile_(profile),
       background_app_count_(0),
+      in_background_mode_(false),
       status_tray_(NULL),
       status_icon_(NULL) {
-  // If background mode is globally disabled, just exit - don't listen for
+  // If background mode is disabled, just exit - don't listen for
   // any notifications.
-  if (!CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableBackgroundMode))
+  if (!command_line->HasSwitch(switches::kEnableBackgroundMode))
     return;
 
   // If the -keep-alive-for-test flag is passed, then always keep chrome running
@@ -84,13 +85,20 @@ BackgroundModeManager::BackgroundModeManager(Profile* profile)
   registrar_.Add(this, NotificationType::APP_TERMINATING,
                  NotificationService::AllSources());
 
-
+  // Listen for changes to the background mode preference.
+  profile_->GetPrefs()->AddPrefObserver(prefs::kBackgroundModeEnabled, this);
 }
 
 BackgroundModeManager::~BackgroundModeManager() {
-  // If we're going away, remove our status tray icon so we don't get any events
-  // from it.
-  RemoveStatusTrayIcon();
+  // We're going away, so exit background mode (does nothing if we aren't in
+  // background mode currently). This is primarily needed for unit tests,
+  // because in an actual running system we'd get an APP_TERMINATING
+  // notification before being destroyed.
+  EndBackgroundMode();
+  // Manually remove our pref observer so we don't get notified for prefs
+  // changes (have to do it manually because we can't use the registrar for
+  // prefs notifications).
+  profile_->GetPrefs()->RemovePrefObserver(prefs::kBackgroundModeEnabled, this);
 }
 
 bool BackgroundModeManager::IsBackgroundModeEnabled() {
@@ -136,14 +144,18 @@ void BackgroundModeManager::Observe(NotificationType type,
         OnBackgroundAppUninstalled();
       break;
     case NotificationType::APP_TERMINATING:
-      // Performing an explicit shutdown, so exit background mode if we were in
-      // background mode.
-      if (background_app_count_ > 0 && IsBackgroundModeEnabled())
-        EndBackgroundMode();
+      // Performing an explicit shutdown, so exit background mode (does nothing
+      // if we aren't in background mode currently).
+      EndBackgroundMode();
       // Shutting down, so don't listen for any more notifications so we don't
       // try to re-enter/exit background mode again.
       registrar_.RemoveAll();
       break;
+    case NotificationType::PREF_CHANGED:
+      DCHECK(0 == Details<std::string>(details).ptr()->compare(
+          prefs::kBackgroundModeEnabled));
+      OnBackgroundModePrefChanged();
+      break;
     default:
       NOTREACHED();
       break;
@@ -154,6 +166,24 @@ bool BackgroundModeManager::IsBackgroundApp(Extension* extension) {
   return extension->HasApiPermission(Extension::kBackgroundPermission);
 }
 
+
+void BackgroundModeManager::OnBackgroundModePrefChanged() {
+  // Background mode has been enabled/disabled in preferences, so update our
+  // state accordingly.
+  if (IsBackgroundModeEnabled() && !in_background_mode_ &&
+      background_app_count_ > 0) {
+    // We should be in background mode, but we're not, so switch to background
+    // mode.
+    EnableLaunchOnStartup(true);
+    StartBackgroundMode();
+  }
+  if (!IsBackgroundModeEnabled() && in_background_mode_) {
+    // We're in background mode, but we shouldn't be any longer.
+    EnableLaunchOnStartup(false);
+    EndBackgroundMode();
+  }
+}
+
 void BackgroundModeManager::OnBackgroundAppLoaded() {
   // When a background app loads, increment our count and also enable
   // KeepAlive mode if the preference is set.
@@ -163,6 +193,13 @@ void BackgroundModeManager::OnBackgroundAppLoaded() {
 }
 
 void BackgroundModeManager::StartBackgroundMode() {
+  // Don't bother putting ourselves in background mode if we're already there.
+  if (in_background_mode_)
+    return;
+
+  // Mark ourselves as running in background mode.
+  in_background_mode_ = true;
+
   // Put ourselves in KeepAlive mode and create a status tray icon.
   BrowserList::StartKeepAlive();
 
@@ -174,12 +211,16 @@ void BackgroundModeManager::OnBackgroundAppUnloaded() {
   // When a background app unloads, decrement our count and also end
   // KeepAlive mode if appropriate.
   background_app_count_--;
-  DCHECK(background_app_count_ == 0);
+  DCHECK(background_app_count_ >= 0);
   if (background_app_count_ == 0 && IsBackgroundModeEnabled())
     EndBackgroundMode();
 }
 
 void BackgroundModeManager::EndBackgroundMode() {
+  if (!in_background_mode_)
+    return;
+  in_background_mode_ = false;
+
   // End KeepAlive mode and blow away our status tray icon.
   BrowserList::EndKeepAlive();
   RemoveStatusTrayIcon();