Add a new field "source" in launchData of chrome.app.runtime.onLaunched() to trace launch source.

chrome/browser/ui/webui/ntp/app_launcher_handler.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/ntp/app_launcher_handler.h"
 
 #include <vector>
 
 #include "apps/metrics_names.h"
 #include "base/auto_reset.h"
@@ skipping 508 matching lines @@
 
   if (disposition == NEW_FOREGROUND_TAB || disposition == NEW_BACKGROUND_TAB ||
       disposition == NEW_WINDOW) {
     // TODO(jamescook): Proper support for background tabs.
     AppLaunchParams params(profile, extension,
                            disposition == NEW_WINDOW ?
                                extensions::LAUNCH_CONTAINER_WINDOW :
                                extensions::LAUNCH_CONTAINER_TAB,
                            disposition);
     params.override_url = GURL(url);
+    params.source = extensions::SOURCE_NEW_TAB_PAGE;
     OpenApplication(params);
   } else {
     // To give a more "launchy" experience when using the NTP launcher, we close
     // it automatically.
     Browser* browser = chrome::FindBrowserWithWebContents(
         web_ui()->GetWebContents());
     WebContents* old_contents = NULL;
     if (browser)
       old_contents = browser->tab_strip_model()->GetActiveWebContents();
 
     AppLaunchParams params(profile, extension,
                            old_contents ? CURRENT_TAB : NEW_FOREGROUND_TAB);
     params.override_url = GURL(url);
+    params.source = extensions::SOURCE_NEW_TAB_PAGE;
     WebContents* new_contents = OpenApplication(params);
 
     // This will also destroy the handler, so do not perform any actions after.
     if (new_contents != old_contents && browser &&
         browser->tab_strip_model()->count() > 1) {
       chrome::CloseWebContents(browser, old_contents, true);
     }
   }
 }
 
@@ skipping 292 matching lines @@
     Browser* browser = chrome::FindBrowserWithWebContents(
         web_ui()->GetWebContents());
     extension_uninstall_dialog_.reset(
         extensions::ExtensionUninstallDialog::Create(
             extension_service_->profile(),
             browser->window()->GetNativeWindow(),
             this));
   }
   return extension_uninstall_dialog_.get();
 }