ntp4: make app-install-via-drag less janky

chrome/browser/extensions/extension_prefs.h

Index: chrome/browser/extensions/extension_prefs.h
diff --git a/chrome/browser/extensions/extension_prefs.h b/chrome/browser/extensions/extension_prefs.h
index 25c2c9a3ab85c879d7f37bc590d9d2fb7b202f2e..cd644633d8fdf5b2840ffcd916d279ad631c4ec4 100644
--- a/chrome/browser/extensions/extension_prefs.h
+++ b/chrome/browser/extensions/extension_prefs.h
@@ -103,7 +103,8 @@ class ExtensionPrefs : public ExtensionContentSettingsStore::Observer {
   // Called when an extension is installed, so that prefs get created.
   void OnExtensionInstalled(const Extension* extension,
                             Extension::State initial_state,
-                            bool from_webstore);
+                            bool from_webstore,
+                            int page_index);
 
   // Called when an extension is uninstalled, so that prefs get cleaned up.
   void OnExtensionUninstalled(const std::string& extension_id,
@@ -273,8 +274,8 @@ class ExtensionPrefs : public ExtensionContentSettingsStore::Observer {
   void SetAppLaunchIndex(const std::string& extension_id, int index);
 
   // Gets the next available application launch index. This is 1 higher than the
-  // highest current application launch index found.
-  int GetNextAppLaunchIndex();
+  // highest current application launch index found for the page |on_page|.
+  int GetNextAppLaunchIndex(int on_page);
 
   // Sets the order the apps should be displayed in the app launcher.
   void SetAppLauncherOrder(const std::vector<std::string>& extension_ids);