From fd13c2e2bc6ddac11e0ef110b68eb0ed856989eb Mon Sep 17 00:00:00 2001
From: Sebastian Kaspari <s.kaspari@gmail.com>
Date: Fri, 23 Oct 2015 12:57:17 +0200
Subject: [PATCH] Bug 1202753 - Tabs tray (Grid): Scroll to selected tab if it
 is not visible. r=margaret

--HG--
extra : commitid : Cm97FTi6pCd
extra : rebase_source : 94961d50ccf77ccfcb884df4f41ab1e970630224
extra : amend_source : eccc38963aa0244ed05eb11481fe06b603d837f8
---
 mobile/android/base/tabs/TabsGridLayout.java | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/mobile/android/base/tabs/TabsGridLayout.java b/mobile/android/base/tabs/TabsGridLayout.java
index 6e6fdc002c9c..da6f81b86a0a 100644
--- a/mobile/android/base/tabs/TabsGridLayout.java
+++ b/mobile/android/base/tabs/TabsGridLayout.java
@@ -171,9 +171,15 @@ class TabsGridLayout extends GridView
         Tabs.registerOnTabsChangedListener(this);
         refreshTabsData();
 
-        Tab currentlySelectedTab = Tabs.getInstance().getSelectedTab();
-        if (lastSelectedTabId != currentlySelectedTab.getId()) {
-            smoothScrollToPosition(tabsAdapter.getPositionForTab(currentlySelectedTab));
+        final Tab currentlySelectedTab = Tabs.getInstance().getSelectedTab();
+        final int position =  currentlySelectedTab != null ? tabsAdapter.getPositionForTab(currentlySelectedTab) : -1;
+        if (position != -1) {
+            final boolean selectionChanged = lastSelectedTabId != currentlySelectedTab.getId();
+            final boolean positionIsVisible = position >= getFirstVisiblePosition() && position <= getLastVisiblePosition();
+
+            if (selectionChanged || !positionIsVisible) {
+                smoothScrollToPosition(position);
+            }
         }
     }