Set Browser::app_name_ in a reasonable way for extension apps.

chrome/browser/ui/browser.cc

Index: chrome/browser/ui/browser.cc
diff --git a/chrome/browser/ui/browser.cc b/chrome/browser/ui/browser.cc
index c3604db859ec62e41be7a923bfb7a22ea547f933..8a5c852cd9a65389d21366ea947bd612cca5e6b3 100644
--- a/chrome/browser/ui/browser.cc
+++ b/chrome/browser/ui/browser.cc
@@ -542,8 +542,13 @@ TabContents* Browser::OpenApplicationWindow(
     url = extension->GetFullLaunchURL();
   }
 
-  // TODO(erikkay) this can't be correct for extensions
-  std::string app_name = web_app::GenerateApplicationNameFromURL(url);
+  std::string app_name;
+  if (extension)
+    app_name =
+        web_app::GenerateApplicationNameFromExtensionId(extension->id());
+  else
+    app_name = web_app::GenerateApplicationNameFromURL(url);
+
   RegisterAppPrefs(app_name);
 
   bool as_panel = extension && (container == extension_misc::LAUNCH_PANEL);