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

chrome/browser/android/shortcut_info.h

Index: chrome/browser/android/shortcut_info.h
diff --git a/chrome/browser/android/shortcut_info.h b/chrome/browser/android/shortcut_info.h
index e641c0b6c9b8f7f839376ce98f3b2e724049e8a5..3b0d01fa61fbcbc80cc98fcbb0c52424db394f51 100644
--- a/chrome/browser/android/shortcut_info.h
+++ b/chrome/browser/android/shortcut_info.h
@@ -12,16 +12,30 @@
 
 // Information needed to create a shortcut via ShortcutHelper.
 struct ShortcutInfo {
+
+  // This enum is used to back a UMA histogram, and must be treated as
+  // append-only.
+  enum Source {
+    SOURCE_UNKNOWN = 0,
+    SOURCE_ADD_TO_HOMESCREEN = 1,
+    SOURCE_APP_BANNER = 2,
+    SOURCE_COUNT = 3
+  };
+
   ShortcutInfo();
   explicit ShortcutInfo(const GURL& shortcut_url);
 
   // Updates the info based on the given |manifest|.
   void UpdateFromManifest(const content::Manifest& manifest);
 
+  // Updates the source of the shortcut.
+  void UpdateSource(const Source source);
+
   GURL url;
   base::string16 title;
   content::Manifest::DisplayMode display;
   blink::WebScreenOrientationLockType orientation;
+  Source source;
 };
 
 #endif  // CHROME_BROWSER_ANDROID_SHORTCUT_INFO_H_