Support setting mouse cursor icon in Android N.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.compositor;
 
 import android.content.Context;
 import android.graphics.Canvas;
 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;
 import android.support.v4.view.accessibility.AccessibilityEventCompat;
 import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat;
 import android.support.v4.widget.ExploreByTouchHelper;
 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;
 import android.widget.FrameLayout;
 
 import org.chromium.base.SysUtils;
 import org.chromium.base.TraceEvent;
 import org.chromium.base.annotations.SuppressFBWarnings;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.compositor.Invalidator.Client;
@@ skipping 141 matching lines @@
     /**
      * Creates a {@link CompositorView}.
      * @param c The Context to create this {@link CompositorView} in.
      */
     public CompositorViewHolder(Context c) {
         super(c);
 
         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.
      * @param attrs The AttributeSet used to create this {@link CompositorView}.
      */
     public CompositorViewHolder(Context c, AttributeSet attrs) {
         super(c, attrs);
 
         internalInit();
     }
@@ skipping 922 matching lines @@
             if (mPixelRect.width() == 0) {
                 mPixelRect.right = mPixelRect.left + 1;
             }
             if (mPixelRect.height() == 0) {
                 mPixelRect.bottom = mPixelRect.top + 1;
             }
             return mPixelRect;
         }
     }
 }