Add a flag to enable open in window for hosted apps on Mac.

chrome/browser/extensions/extension_util.h

Index: chrome/browser/extensions/extension_util.h
diff --git a/chrome/browser/extensions/extension_util.h b/chrome/browser/extensions/extension_util.h
index e502d0d45e67d17edda776331f76acf5c7e38183..aa8f613d3ecc98891623d21bf27c8d4c3df09315 100644
--- a/chrome/browser/extensions/extension_util.h
+++ b/chrome/browser/extensions/extension_util.h
@@ -125,6 +125,10 @@ const gfx::ImageSkia& GetDefaultAppIcon();
 // feature is stable.
 bool IsNewBookmarkAppsEnabled();
 
+// TODO(dominickn): http://crbug.com/517682: Remove this entirely once
+// open in window is stable on Mac.
+bool CanHostedAppsOpenInWindows();
+
 // Returns true for custodian-installed extensions in a supervised profile.
 bool IsExtensionSupervised(const Extension* extension, Profile* profile);