Fix snapping in Android horizontal tab switcher when reloading from c…

…old start

We currently have a bug in the new horizontal tab switcher on Android where if
tabs get reloaded after a cold start, the snap distance is not set properly, so
the snapping behavior doesn't work properly. The fix is to update the snap
distance in NonOverlappingStack#notifySizeChanged() in addition to
contextChanged() (apparently when reloading tabs, contextChanged() is not called
again after the StackLayout's size is properly set).

Bug: 846961, 831359
Change-Id: I8c1be9f38889d6d1c45adefeb51af30d6a8bb4e3
Reviewed-on: https://chromium-review.googlesource.com/1081091
Reviewed-by: Matthew Jones <[email protected]>
Commit-Queue: Ryan Landay <[email protected]>
Cr-Original-Commit-Position: refs/heads/master@{#563647}(cherry picked from commit a73bfcd)
Reviewed-on: https://chromium-review.googlesource.com/1082852
Reviewed-by: Ryan Landay <[email protected]>
Cr-Commit-Position: refs/branch-heads/3440@{#94}
Cr-Branched-From: 010ddcf-refs/heads/master@{#561733}

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/phone/stack/NonOverlappingStack.java

@@ -89,9 +89,7 @@ protected boolean evenOutTabs(float amount, boolean allowReverseDirection) {
         return false;
     }
 
-    @Override
-    public void contextChanged(Context context) {
-        super.contextChanged(context);
+    private void updateScrollSnap() {
         mScroller.setFrictionMultiplier(FRICTION_MULTIPLIER);
         // This is what computeSpacing() returns when there are >= 2 tabs
         final int snapDistance =
@@ -102,6 +100,18 @@ public void contextChanged(Context context) {
         mScroller.setYSnapDistance(snapDistance);
     }
 
+    @Override
+    public void contextChanged(Context context) {
+        super.contextChanged(context);
+        updateScrollSnap();
+    }
+
+    @Override
+    public void notifySizeChanged(float width, float height, int orientation) {
+        super.notifySizeChanged(width, height, orientation);
+        updateScrollSnap();
+    }
+
     @Override
     public void onPinch(long time, float x0, float y0, float x1, float y1, boolean firstEvent) {
         return;