Add UMA metrics to track the source of homescreen icons on launch.

chrome/browser/android/shortcut_info.cc

 // Copyright 2015 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/android/shortcut_info.h"
 
 ShortcutInfo::ShortcutInfo()
     : display(content::Manifest::DISPLAY_MODE_BROWSER),
-      orientation(blink::WebScreenOrientationLockDefault) {
+      orientation(blink::WebScreenOrientationLockDefault),
+      source(SOURCE_ADD_TO_HOMESCREEN) {
 }
 
 ShortcutInfo::ShortcutInfo(const GURL& shortcut_url)
     : url(shortcut_url),
       display(content::Manifest::DISPLAY_MODE_BROWSER),
-      orientation(blink::WebScreenOrientationLockDefault) {
+      orientation(blink::WebScreenOrientationLockDefault),
+      source(SOURCE_ADD_TO_HOMESCREEN) {
 }
 
 void ShortcutInfo::UpdateFromManifest(const content::Manifest& manifest) {
   if (!manifest.short_name.is_null())
     title = manifest.short_name.string();
   else if (!manifest.name.is_null())
     title = manifest.name.string();
 
   // Set the url based on the manifest value, if any.
   if (manifest.start_url.is_valid())
@@ skipping 12 matching lines @@
 
   // Set the orientation based on the manifest value, if any.
   if (manifest.orientation != blink::WebScreenOrientationLockDefault) {
     // Ignore the orientation if the display mode is different from
     // 'standalone'.
     // TODO(mlamouri): send a message to the developer console about this.
     if (display == content::Manifest::DISPLAY_MODE_STANDALONE)
       orientation = manifest.orientation;
   }
 }
+
+void ShortcutInfo::UpdateSource(const Source new_source) {
+  source = new_source;
+}