[NTP Snippets] Track impression only when 2/3 of a card is visible (rather than 1/3)

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..11f6cb037e79c31e0ffcbca2be49d62c3a33431e 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
@@ -17,7 +17,7 @@ import android.view.ViewTreeObserver;
 public class ImpressionTracker
         implements ViewTreeObserver.OnPreDrawListener, View.OnAttachStateChangeListener {
     /**
-     * The Listener will be called back on each impression. Whenever at least 1/3 of the view's
+     * The Listener will be called back on each impression. Whenever at least 2/3 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}.
@@ -92,8 +92,8 @@ public class ImpressionTracker
         if (parent != null) {
             Rect rect = new Rect(0, 0, mView.getWidth(), mView.getHeight());
             parent.getChildVisibleRect(mView, rect, null);
-            // Track impression if at least one third of the view is visible.
-            if (rect.height() >= mView.getHeight() / 3) {
+            // Track impression if at least 2/3 of the view is visible.
+            if (rect.height() >= 2 * mView.getHeight() / 3) {
                 mTriggered = true;
                 mListener.onImpression();
             }