Cleanup: Pull some browser keep alive functions into its own file.

chrome/browser/background/background_mode_manager.cc

Index: chrome/browser/background/background_mode_manager.cc
diff --git a/chrome/browser/background/background_mode_manager.cc b/chrome/browser/background/background_mode_manager.cc
index 5bd2c6c5fa8186d2801aa1bd30ec1263283e66fd..117da57f8ae2147e02706c2163d56e44d18b2bb0 100644
--- a/chrome/browser/background/background_mode_manager.cc
+++ b/chrome/browser/background/background_mode_manager.cc
@@ -28,6 +28,7 @@
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/lifetime/application_lifetime.h"
+#include "chrome/browser/lifetime/browser_keep_alive.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_info_cache.h"
 #include "chrome/browser/profiles/profile_manager.h"
@@ -121,6 +122,14 @@ void RecordMenuItemClick(MenuItem item) {
   UMA_HISTOGRAM_ENUMERATION("BackgroundMode.MenuItemClick", item,
                             MENU_ITEM_NUM_STATES);
 }
+
+// Helper function for DecrementKeepAliveCountForStartup() to actually decrement
+// the keep alive.
+void DoDecrementKeepAliveCountForStartup(
+    scoped_ptr<browser_lifetime::ScopedKeepAlive> keep_alive) {
+  keep_alive.reset();  // Explicitly reset().
+}
+
 }  // namespace
 
 BackgroundModeManager::BackgroundModeData::BackgroundModeData(
@@ -310,10 +319,8 @@ BackgroundModeManager::BackgroundModeManager(
       status_icon_(NULL),
       context_menu_(NULL),
       in_background_mode_(false),
-      keep_alive_for_startup_(false),
       keep_alive_for_test_(false),
       background_mode_suspended_(false),
-      keeping_alive_(false),
       weak_factory_(this) {
   // We should never start up if there is no browser process or if we are
   // currently quitting.
@@ -342,8 +349,7 @@ BackgroundModeManager::BackgroundModeManager(
   // extensions, at which point we should either run in background mode (if
   // there are background apps) or exit if there are none.
   if (command_line.HasSwitch(switches::kNoStartupWindow)) {
-    keep_alive_for_startup_ = true;
-    chrome::IncrementKeepAliveCount();
+    keep_alive_for_startup_.reset(new browser_lifetime::ScopedKeepAlive);
   } else {
     // Otherwise, start with background mode suspended in case we're launching
     // in a mode that doesn't open a browser window. It will be resumed when the
@@ -680,7 +686,7 @@ void BackgroundModeManager::ExecuteCommand(int command_id, int event_flags) {
       // Background mode must already be enabled (as otherwise this menu would
       // not be visible).
       DCHECK(IsBackgroundModePrefEnabled());
-      DCHECK(chrome::WillKeepAlive());
+      DCHECK(browser_lifetime::WillKeepAlive());
 
       RecordMenuItemClick(MENU_ITEM_KEEP_RUNNING);
 
@@ -708,12 +714,13 @@ void BackgroundModeManager::ExecuteCommand(int command_id, int event_flags) {
 //  BackgroundModeManager, private
 void BackgroundModeManager::DecrementKeepAliveCountForStartup() {
   if (keep_alive_for_startup_) {
-    keep_alive_for_startup_ = false;
     // We call this via the message queue to make sure we don't try to end
     // keep-alive (which can shutdown Chrome) before the message loop has
     // started.
     base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(&chrome::DecrementKeepAliveCount));
+        FROM_HERE,
+        base::Bind(&DoDecrementKeepAliveCountForStartup,
+                   base::Passed(&keep_alive_for_startup_)));
   }
 }
 
@@ -792,9 +799,9 @@ void BackgroundModeManager::ResumeBackgroundMode() {
 
 void BackgroundModeManager::UpdateKeepAliveAndTrayIcon() {
   if (in_background_mode_ && !background_mode_suspended_) {
-    if (!keeping_alive_) {
-      keeping_alive_ = true;
-      chrome::IncrementKeepAliveCount();
+    if (!keep_alive_for_background_mode_) {
+      keep_alive_for_background_mode_.reset(
+          new browser_lifetime::ScopedKeepAlive);
 
 #if defined(OS_WIN)
       browser_watcher::ExitFunnel::RecordSingleEvent(
@@ -806,9 +813,8 @@ void BackgroundModeManager::UpdateKeepAliveAndTrayIcon() {
   }
 
   RemoveStatusTrayIcon();
-  if (keeping_alive_) {
-    keeping_alive_ = false;
-    chrome::DecrementKeepAliveCount();
+  if (keep_alive_for_background_mode_) {
+    keep_alive_for_background_mode_.reset();
 
 #if defined(OS_WIN)
     browser_watcher::ExitFunnel::RecordSingleEvent(
@@ -867,7 +873,7 @@ int BackgroundModeManager::GetBackgroundClientCount() const {
   // clients.
   for (const auto& it : background_mode_data_)
     count += it.second->GetBackgroundClientCount();
-  DCHECK(count >= 0);
+  DCHECK_GE(count, 0);
   return count;
 }