📰 Make the MORE button more configurable

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ImpressionTracker.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ImpressionTracker.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ImpressionTracker.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ImpressionTracker.java
index 9fefe6faa696616de5c7826003eb9633e8e83bd8..5dff60b4c8ddb11aaf66fc0374c4a43fdac20411 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ImpressionTracker.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ImpressionTracker.java
@@ -19,11 +19,12 @@
     /**
      * The Listener will be called back on each impression. Whenever at least 1/3 of the view's
      * height is visible, that counts as an impression. Note that this will get called often while
-     * the view is visible; it's the implementer's responsibility to count only one impression or
-     * reset the {@link ImpressionTracker}.
+     * the view is visible; it's the implementer's responsibility to count only one impression,
+     * reset the {@link ImpressionTracker} or configure it to fire only once.

[PEConn, 2016/11/01 11:05:43]

Rewrite this comment a bit, maybe:
This will be called only once if the ImpressionTracker is initialized with
isOneShot=true or multiple times if not. Further calls can be prevented by
calling reset().

[dgn, 2016/11/01 14:48:11]

Thanks! that's better yes

      *
      * @see ImpressionTracker#reset(View)
      * @see ImpressionTracker#wasTriggered()
+     * @see ImpressionTracker#ImpressionTracker(View, Listener, boolean)
      */
     public interface Listener {
         void onImpression();
@@ -37,13 +38,15 @@
     private View mView;
     private final Listener mListener;
     private boolean mTriggered;
+    private boolean mIsOneShot;

[PEConn, 2016/11/01 11:05:44]

I think it would be nicer to have two separate classes - a
MultipleCallImpressionTracker and a OneShotImpressionTracker, but given there is
so much code overlap, maybe this is OK.

[dgn, 2016/11/01 14:48:11]

Ok I'll do all that in a separate CL.

 
     /**
      * Creates an {@link ImpressionTracker}. {@code view} can be {@code null} if the tracked should
      * not be registered on any View at construction time.
      */
-    public ImpressionTracker(@Nullable View view, Listener listener) {
+    public ImpressionTracker(@Nullable View view, Listener listener, boolean isOneShot) {

[PEConn, 2016/11/01 11:05:43]

Add some Javadoc for isOneShot?

[dgn, 2016/11/01 14:48:11]

Done.

         mListener = listener;
+        mIsOneShot = isOneShot;
         reset(view);
     }
 
@@ -96,6 +99,7 @@ public boolean onPreDraw() {
             if (rect.height() >= mView.getHeight() / 3) {
                 mTriggered = true;
                 mListener.onImpression();
+                if (mIsOneShot) reset(null);
             }
         }
         // Proceed with the current drawing pass.