Turn background mode on by default on windows.

Added a common routine to check whether background mode/background page tracking
should be enabled with logic to enable it by default on windows.

BUG=59980
TEST=existing tests suffice

Review URL: http://codereview.chromium.org/5296003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@67235 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 41 insertions, 10 deletions

diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 0000aa5..722cd5d 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -136,7 +136,7 @@ const Experiment kExperiments[] = {
     "background-webapps",  // FLAGS:RECORD_UMA
     IDS_FLAGS_BACKGROUND_WEBAPPS_NAME,
     IDS_FLAGS_BACKGROUND_WEBAPPS_DESCRIPTION,
-    kOsAll,
+    kOsMac | kOsLinux | kOsCrOS,  // Enabled by default on windows
     switches::kEnableBackgroundMode
   },
   {
diff --git a/chrome/browser/background_mode_manager.cc b/chrome/browser/background_mode_manager.cc
index 8f78dfb..99c0ee3 100644
--- a/chrome/browser/background_mode_manager.cc
+++ b/chrome/browser/background_mode_manager.cc
@@ -150,10 +150,9 @@ BackgroundModeManager::BackgroundModeManager(Profile* profile,
       keep_alive_for_startup_(false),
       status_tray_(NULL),
       status_icon_(NULL) {
-  // If background mode or apps are disabled, just exit - don't listen for
-  // any notifications.
-  if (!command_line->HasSwitch(switches::kEnableBackgroundMode) ||
-      command_line->HasSwitch(switches::kDisableExtensions))
+  // If background mode is disabled, just exit - don't listen for any
+  // notifications.
+  if (!IsBackgroundModeEnabled(command_line))
     return;
 
   // Keep the browser alive until extensions are done loading - this is needed
@@ -552,3 +551,23 @@ Browser* BackgroundModeManager::GetBrowserWindow() {
 void BackgroundModeManager::RegisterUserPrefs(PrefService* prefs) {
   prefs->RegisterBooleanPref(prefs::kLaunchOnStartupResetAllowed, false);
 }
+
+// static
+bool BackgroundModeManager::IsBackgroundModeEnabled(
+    const CommandLine* command_line) {
+
+  // Background mode is disabled if the appropriate flag is passed, or if
+  // extensions are disabled.
+  bool background_mode_enabled =
+      !command_line->HasSwitch(switches::kDisableBackgroundMode) &&
+      !command_line->HasSwitch(switches::kDisableExtensions);
+#if !defined(OS_WIN)
+  // BackgroundMode is enabled by default on windows. On other platforms, it
+  // is enabled via about:flags.
+  background_mode_enabled = background_mode_enabled &&
+      command_line->HasSwitch(switches::kEnableBackgroundMode);
+#endif
+
+  return background_mode_enabled;
+}
+
diff --git a/chrome/browser/background_mode_manager.h b/chrome/browser/background_mode_manager.h
index dbae6e5..6da40ec 100644
--- a/chrome/browser/background_mode_manager.h
+++ b/chrome/browser/background_mode_manager.h
@@ -46,6 +46,8 @@ class BackgroundModeManager
 
   static void RegisterUserPrefs(PrefService* prefs);
 
+  static bool IsBackgroundModeEnabled(const CommandLine* command_line);
+
  private:
   friend class TestBackgroundModeManager;
   friend class BackgroundModeManagerTest;
diff --git a/chrome/browser/background_page_tracker.cc b/chrome/browser/background_page_tracker.cc
index 8647e5d..515ca75 100644
--- a/chrome/browser/background_page_tracker.cc
+++ b/chrome/browser/background_page_tracker.cc
@@ -11,6 +11,7 @@
 #include "base/values.h"
 #include "chrome/browser/background_application_list_model.h"
 #include "chrome/browser/background_contents_service.h"
+#include "chrome/browser/background_mode_manager.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/extensions/extensions_service.h"
 #include "chrome/browser/prefs/pref_service.h"
@@ -134,11 +135,13 @@ PrefService* BackgroundPageTracker::GetPrefService() {
 }
 
 bool BackgroundPageTracker::IsEnabled() {
-  // BackgroundPageTracker is enabled if both extensions and background mode
-  // are enabled.
+  // Disable the background page tracker for unittests.
+  if (!g_browser_process->local_state())
+    return false;
+
+  // BackgroundPageTracker is enabled if background mode is enabled.
   CommandLine* command_line = CommandLine::ForCurrentProcess();
-  return command_line->HasSwitch(switches::kEnableBackgroundMode) &&
-         !command_line->HasSwitch(switches::kDisableExtensions);
+  return BackgroundModeManager::IsBackgroundModeEnabled(command_line);
 }
 
 void BackgroundPageTracker::Observe(NotificationType type,
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 8e99e8e..e036dd0 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -157,6 +157,11 @@ const char kDisableAudio[]                  = "disable-audio";
 const char kDisableAuthNegotiateCnameLookup[] =
     "disable-auth-negotiate-cname-lookup";
 
+// Disable background mode (background apps will not keep chrome running in the
+// background). This has priority over the kEnableBackgroundMode flag which is
+// settable via about:labs.
+const char kDisableBackgroundMode[] = "disable-background-mode";
+
 // Disable several subsystems which run network requests in the background.
 // This is for use when doing network performance testing to avoid noise
 // in the measurements.
@@ -390,7 +395,8 @@ const char kEnableAppLauncher[]             = "enable-app-launcher";
 const char kEnableAuthNegotiatePort[]       = "enable-auth-negotiate-port";
 
 // Enable background mode (background apps will keep chrome running in the
-// background and allow chrome to launch on startup).
+// background and allow chrome to launch on startup). Has no effect on Windows
+// because background mode is enabled there by default.
 const char kEnableBackgroundMode[] = "enable-background-mode";
 
 // Enables the benchmarking extensions.
diff --git a/chrome/common/chrome_switches.h b/chrome/common/chrome_switches.h
index 1154171..152e5af 100644
--- a/chrome/common/chrome_switches.h
+++ b/chrome/common/chrome_switches.h
@@ -55,6 +55,7 @@ extern const char kDisableAltWinstation[];
 extern const char kDisableApplicationCache[];
 extern const char kDisableAudio[];
 extern const char kDisableAuthNegotiateCnameLookup[];
+extern const char kDisableBackgroundMode[];
 extern const char kDisableBackgroundNetworking[];
 extern const char kDisableBackingStoreLimit[];
 extern const char kDisableConnectBackupJobs[];