Replace Increment/DecrementKeepAliveCount by ScopedKeepAlives

chrome/browser/lifetime/application_lifetime_aura.cc

Index: chrome/browser/lifetime/application_lifetime_aura.cc
diff --git a/chrome/browser/lifetime/application_lifetime_aura.cc b/chrome/browser/lifetime/application_lifetime_aura.cc
index 12c061388fc069fb622a6b6afef0266e5b5b712d..fd970ca3ac609c03148b9ac1b757780984460941 100644
--- a/chrome/browser/lifetime/application_lifetime_aura.cc
+++ b/chrome/browser/lifetime/application_lifetime_aura.cc
@@ -7,6 +7,7 @@
 #include "base/command_line.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
+#include "chrome/browser/browser_process_platform_part.h"
 #include "chrome/browser/notifications/notification_ui_manager.h"
 #include "chrome/common/chrome_switches.h"
 #include "ui/aura/client/capture_client.h"
@@ -40,8 +41,8 @@ void HandleAppExitingForPlatform() {
 #if defined(OS_CHROMEOS)
   if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableZeroBrowsersOpenForTests)) {
-    // App is exiting, call DecrementKeepAliveCount() on behalf of Aura Shell.
-    DecrementKeepAliveCount();
+    // App is exiting, release the keep alive on behalf of Aura Shell.
+    g_browser_process->platform_part()->UnregisterKeepAlive();

[sky, 2016/03/10 04:18:20]

Seems wrong that this has to reach out to other code to cancel a keep alive.

[dgn, 2016/03/10 18:31:51]

Hum... We are stateless here, while we need something to hold the reference to
the KeepAlive. The lifetime of that one is around the one of the whole browser
and it's chromeos specific, so it seemed to me like a reasonable place. I'm not
very familiar with the architecture though. 

I moved it to application_lifetime_aura.cc in the new patch. Is it better?
That's a global static so that might cause some issues in tests.

[sky, 2016/03/10 20:38:36]

I realize why you did the change. I was more commenting it that it's unfortunate
the code is like this. I prefer the previous approach. That at least has better
scoping.

[dgn, 2016/03/11 17:11:49]

Ah ok. I reverted that part then.

     // Make sure we have notified the session manager that we are exiting.
     // This might be called from FastShutdown() or CloseAllBrowsers(), but not
     // if something prevents a browser from closing before SetTryingToQuit()