Photo Picker dialog: Add UMA statistics.

chrome/android/java/src/org/chromium/chrome/browser/photo_picker/PickerCategoryView.java

Index: chrome/android/java/src/org/chromium/chrome/browser/photo_picker/PickerCategoryView.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/photo_picker/PickerCategoryView.java b/chrome/android/java/src/org/chromium/chrome/browser/photo_picker/PickerCategoryView.java
index 24bdc226e65f2ba107dbd0408fd2e8f48bb92f06..81f6f7115fe98afa11d396d5bc17728e779fc698 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/photo_picker/PickerCategoryView.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/photo_picker/PickerCategoryView.java
@@ -19,6 +19,7 @@ import android.widget.Button;
 import android.widget.RelativeLayout;
 
 import org.chromium.base.VisibleForTesting;
+import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.widget.selection.SelectableListLayout;
 import org.chromium.chrome.browser.widget.selection.SelectionDelegate;
@@ -37,6 +38,18 @@ public class PickerCategoryView extends RelativeLayout
                    DecoderServiceHost.ServiceReadyCallback, View.OnClickListener {
     private static final int KILOBYTE = 1024;
 
+    // The UMA key for tracking the actions taken in the dialog.
+    private static final String HISTOGRAM_NAME = "Android.PhotoPicker.DialogAction";

[Theresa, 2017/05/31 18:40:02]

optional nit: The downside to using a static final String is that our presubmit
scripts can't check for missing histograms. Typically we just duplicate the
string in-line in the calls to record histograms so that the presubmit checks
work.

[Finnur, 2017/06/01 15:13:55]

Done.

+
+    // Note: these values must match the PhotoPickerDialogAction enum values in histograms.xml.
+    // Only add new values at the end, right before ACTIONS. We depend on these specific values in
+    // UMA histograms.
+    private static final int ACTION_CANCEL = 0;
+    private static final int ACTION_PHOTO_PICKED = 1;
+    private static final int ACTION_NEW_PHOTO = 2;
+    private static final int ACTION_BROWSE = 3;
+    private static final int NUM_ACTIONS = 4;

[Theresa, 2017/05/31 18:40:02]

nit: ACTIONS_BOUNDARY is more consistent with how we usually specify histogram
enum boundaries.

[Finnur, 2017/06/01 15:13:55]

Done.

+
     // The dialog that owns us.
     private PhotoPickerDialog mDialog;
 
@@ -195,6 +208,8 @@ public class PickerCategoryView extends RelativeLayout
         mDialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
             @Override
             public void onCancel(DialogInterface dialog) {
+                RecordHistogram.recordEnumeratedHistogram(
+                        HISTOGRAM_NAME, ACTION_CANCEL, NUM_ACTIONS);
                 mListener.onPickerUserAction(PhotoPickerListener.Action.CANCEL, null);
             }
         });
@@ -232,8 +247,11 @@ public class PickerCategoryView extends RelativeLayout
     @Override
     public void onClick(View view) {
         if (view.getId() == R.id.done) {
+            RecordHistogram.recordEnumeratedHistogram(
+                    HISTOGRAM_NAME, ACTION_PHOTO_PICKED, NUM_ACTIONS);
             notifyPhotosSelected();
         } else {
+            RecordHistogram.recordEnumeratedHistogram(HISTOGRAM_NAME, ACTION_CANCEL, NUM_ACTIONS);
             mListener.onPickerUserAction(PhotoPickerListener.Action.CANCEL, null);
         }
 
@@ -284,6 +302,7 @@ public class PickerCategoryView extends RelativeLayout
      * Notifies the listener that the user selected to launch the gallery.
      */
     public void showGallery() {
+        RecordHistogram.recordEnumeratedHistogram(HISTOGRAM_NAME, ACTION_BROWSE, NUM_ACTIONS);
         mListener.onPickerUserAction(PhotoPickerListener.Action.LAUNCH_GALLERY, null);
     }
 
@@ -291,6 +310,7 @@ public class PickerCategoryView extends RelativeLayout
      * Notifies the listener that the user selected to launch the camera intent.
      */
     public void showCamera() {
+        RecordHistogram.recordEnumeratedHistogram(HISTOGRAM_NAME, ACTION_NEW_PHOTO, NUM_ACTIONS);
         mListener.onPickerUserAction(PhotoPickerListener.Action.LAUNCH_CAMERA, null);
     }