Add UMA metrics for Bookmark widgets.

chrome/android/java/src/org/chromium/chrome/browser/bookmarkswidget/BookmarkThumbnailWidgetService.java

Index: chrome/android/java/src/org/chromium/chrome/browser/bookmarkswidget/BookmarkThumbnailWidgetService.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/bookmarkswidget/BookmarkThumbnailWidgetService.java b/chrome/android/java/src/org/chromium/chrome/browser/bookmarkswidget/BookmarkThumbnailWidgetService.java
index ec36536e14df4441c2af286635231c4c0c744426..a251faa5d074c05703b5554e0bd93317e88e7b7f 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/bookmarkswidget/BookmarkThumbnailWidgetService.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/bookmarkswidget/BookmarkThumbnailWidgetService.java
@@ -24,6 +24,7 @@ import com.google.android.apps.chrome.appwidget.bookmarks.BookmarkThumbnailWidge
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.annotations.SuppressFBWarnings;
 import org.chromium.base.library_loader.ProcessInitException;
+import org.chromium.base.metrics.RecordUserAction;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.ChromeApplication;
 import org.chromium.chrome.browser.ChromeBrowserProvider.BookmarkNode;
@@ -113,6 +114,7 @@ public class BookmarkThumbnailWidgetService extends RemoteViewsService {
                 // can work, so kill the whole application not just the activity
                 System.exit(-1);
             }
+            recordWidgetAdded();
             mUpdateListener = new BookmarkWidgetUpdateListener(mContext, this);
         }
 
@@ -163,6 +165,14 @@ public class BookmarkThumbnailWidgetService extends RemoteViewsService {
                         .putExtra(BookmarkColumns.ID, folderId));
         }
 
+        private void recordWidgetAdded() {

[newt (away), 2015/07/15 02:56:00]

I'd call this something like maybeRecordWidgetAdded() since this method gets
called lot (e.g. every time the device is restarted, or whenever the user clicks
a folder inside the widget and Chrome isn't running), and every time except the
first, it won't record anything. It's probably also worth commenting that you're
using the absence of STATE_CURRENT_FOLDER to signal that the widget is new. Or
you could rename this method to isWidgetNewlyCreated() and put this code in
onCreate():

  if (isWidgetNewlyCreated()) {
    RecordUserAction.record("BookmarkNavigatorWidgetAdded");
  }

That seems clear enough not to need many/any comments.

[aurimas (slooooooooow), 2015/07/16 01:15:31]

Done

+            long currentFolder = mPreferences.getLong(STATE_CURRENT_FOLDER,
+                    ChromeBrowserProviderClient.INVALID_BOOKMARK_ID);
+            if (currentFolder == ChromeBrowserProviderClient.INVALID_BOOKMARK_ID) {
+                RecordUserAction.record("BookmarkNavigatorWidgetAdded");
+            }
+        }
+
         // Performs the required checks to trigger an update of the widget after changing the sync
         // enable settings. The required provider methods cannot be accessed in the UI thread.
         private class SyncEnabledStatusUpdatedTask extends AsyncTask<Void, Void, Void> {