Fix crash on J,K while swiping on custom tabs title

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerDocument.java

Index: chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerDocument.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerDocument.java b/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerDocument.java
index 8bf6d69d2f654b67ad4b24c774e90356a1552a77..79b099f68f56f88d7deda5b55f5765690c3e4ffa 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerDocument.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerDocument.java
@@ -445,6 +445,7 @@ public class LayoutManagerDocument extends LayoutManager
         public boolean isSwipeEnabled(ScrollDirection direction) {
             FullscreenManager manager = mHost.getFullscreenManager();
             if (getActiveLayout() != mStaticLayout
+                    || !FeatureUtilities.isDocumentModeEligible(mHost.getContext())

[David Trainor- moved to gerrit, 2015/09/01 22:23:50]

Now that I think about it, I think this is supposed to work with document mode
right?  We use model.setIndex() to force the activity swap.  I'm actually
surprised this is enabled though.  I think the issue is you're in "tabbed
chrome" but in a "custom tab" right?

[Yusuf, 2015/09/01 22:29:42]

Yes, we are in tabbed mode since it is J or K. It is not "really" enabled. The
base class is LayoutManagerDocument and all related impl assumes since you are
using this class and not overriding anything running L APIs is OK which is imo
the main problem here.

We have @TargetAPI(Lollipop) above but no formal code that blocks the use of
that API. This line fixes that. CustomTabActivity by using the simplest, parent
LayoutManager starting calling that API on J and K devices. 

[David Trainor- moved to gerrit, 2015/09/01 23:23:53]

Ok that works for me and makes sense! :)

                     || !DeviceClassManager.enableToolbarSwipe(
                                FeatureUtilities.isDocumentMode(mHost.getContext()))
                     || (manager != null && manager.getPersistentFullscreenMode())) {