Support setting mouse cursor icon in Android N.

chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolder.java

Index: chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolder.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolder.java b/chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolder.java
index 822280d829191aefd11704e110a3d0684fa7f0a7..d52605e8f85b0cd6377928e6700d1c3dcb57ee93 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolder.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolder.java
@@ -10,6 +10,7 @@ import android.graphics.Color;
 import android.graphics.Paint;
 import android.graphics.Rect;
 import android.graphics.RectF;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
 import android.support.v4.view.ViewCompat;
@@ -20,6 +21,7 @@ import android.util.AttributeSet;
 import android.util.Pair;
 import android.view.DragEvent;
 import android.view.MotionEvent;
+import android.view.PointerIcon;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.accessibility.AccessibilityEvent;
@@ -181,6 +183,14 @@ public class CompositorViewHolder extends FrameLayout
         internalInit();
     }
 
+    @Override
+    public PointerIcon onResolvePointerIcon(MotionEvent event, int pointerIndex) {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) return null;
+        ContentViewCore content = getActiveContent();

[Ted C, 2017/08/09 04:30:54]

I still don't see how this would work if you're in the tab switcher.  What makes
this return null?  Is it because the container view is not attached and
therefore something in the android framework returns null?

Or are we sending a blur to the webcontents when the tab is detached and thus
ViewAndroidDelegate gets updated?

[jaebaek, 2017/08/09 06:38:17]

In the tab switcher, the ContentViewCore is null, so the null checking must be
here. I am not sure about other cases.

[Ted C, 2017/08/09 16:30:55]

Sorry to keep belaboring the point, but that is definitely not true.  When
entering the tab switcher on phones (at least the high end ones), the tab
remains selected in the model and thus has a valid CVC.

I just added logging in CompositorViewHolder#didSwapFrame and the CVC is never
null in the tab switcher unless I close all the tabs.

So, I still very much believe this is not working as you expect.

[jaebaek, 2017/08/11 00:47:35]

As discussed this in offline, I replaced this with the activeView.

+        if (content == null) return null;
+        return content.getContainerView().onResolvePointerIcon(event, pointerIndex);
+    }
+
     /**
      * Creates a {@link CompositorView}.
      * @param c     The Context to create this {@link CompositorView} in.