Use window singleton API in the App Developer Tool and simplify the code.

chrome/browser/resources/apps_debugger/background.js

Index: chrome/browser/resources/apps_debugger/background.js
diff --git a/chrome/browser/resources/apps_debugger/background.js b/chrome/browser/resources/apps_debugger/background.js
index d5042da674f96253b73ca5b698473784f320f2cd..0b16d8c47163052fc2921847ba5403bad3b89bbb 100644
--- a/chrome/browser/resources/apps_debugger/background.js
+++ b/chrome/browser/resources/apps_debugger/background.js
@@ -4,17 +4,11 @@
 
 var mainWindow = null;
 chrome.app.runtime.onLaunched.addListener(function() {
-  if (mainWindow && !mainWindow.contentWindow.closed) {

[Dan Beam, 2013/05/23 19:58:42]

so removing this lets there be multiple apps instead of re-focusing the same
one?

-    mainWindow.focus();
-  } else {
-    chrome.app.window.create('main.html', {
-      id: 'apps_debugger',
-      minHeight: 600,
-      minWidth: 800,
-      height: 600,
-      width: 800,
-    }, function(win) {
-      mainWindow = win;
-    });
-  }
+  chrome.app.window.create('main.html', {
+    id: 'apps_devtool',
+    minHeight: 600,
+    minWidth: 800,
+    height: 600,
+    width: 800,

[Dan Beam, 2013/05/23 20:12:38]

where's

  singleton: true,

?

[Gaurav, 2013/05/23 20:23:59]

I think it will be good to add it explicity.
On 2013/05/23 20:12:38, Dan Beam wrote:

+  });
 });