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

chrome/browser/devtools/devtools_sanity_browsertest.cc

Index: chrome/browser/devtools/devtools_sanity_browsertest.cc
diff --git a/chrome/browser/devtools/devtools_sanity_browsertest.cc b/chrome/browser/devtools/devtools_sanity_browsertest.cc
index e8fc89c1a1fe1f95bb844b58132934314e4c3bc0..4eded2b632c5a2298608df4845a7fb20cf5077bb 100644
--- a/chrome/browser/devtools/devtools_sanity_browsertest.cc
+++ b/chrome/browser/devtools/devtools_sanity_browsertest.cc
@@ -25,6 +25,7 @@
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/unpacked_installer.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/ui/browser.h"
 #include "chrome/browser/ui/browser_commands.h"
@@ -180,8 +181,9 @@ class DevToolsSanityTest : public InProcessBrowserTest {
 class DevToolsWindowBeforeUnloadObserver
     : public content::WebContentsObserver {
  public:
-  explicit DevToolsWindowBeforeUnloadObserver(DevToolsWindow*);
+  explicit DevToolsWindowBeforeUnloadObserver(DevToolsWindow* devtools_window);
   void Wait();
+
  private:
   // Invoked when the beforeunload handler fires.
   void BeforeUnloadFired(const base::TimeTicks& proceed_time) override;
@@ -709,7 +711,7 @@ IN_PROC_BROWSER_TEST_F(DevToolsBeforeUnloadTest,
     content::WindowedNotificationObserver close_observer(
         chrome::NOTIFICATION_BROWSER_CLOSED,
         content::Source<Browser>(browser()));
-    chrome::IncrementKeepAliveCount();
+    browser_lifetime::IncrementKeepAliveCount();
     chrome::CloseAllBrowsers();
     AcceptModalDialog();
     AcceptModalDialog();