Support setting mouse cursor icon in Android N.

chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java

Index: chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java b/chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java
index 226cace74e23672010ad4fb4108e4818b1ca27bd..8a34c3f12e10e568e4df2ada1356f177db7cd493 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java
@@ -6,6 +6,7 @@ package org.chromium.chrome.browser.fullscreen;
 
 import android.app.Activity;
 import android.content.res.Resources;
+import android.os.Build;
 import android.view.Gravity;
 import android.view.MotionEvent;
 import android.view.View;
@@ -524,6 +525,12 @@ public class ChromeFullscreenManager
                 mListeners.get(i).onControlsOffsetChanged(
                         getTopControlOffset(), getBottomControlOffset(), needsAnimate);
             }
+
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {

[Ted C, 2017/07/21 00:15:25]

why is this needed?  this is while the top controls are scrolling off right? 
The view is made to be gone in that case, so do we still need this?

[jaebaek, 2017/07/21 10:03:04]

The view is still present at its location (i.e., the visibility is not gone)
though it is not visible. So the wrong icons (such as text I-beam) will be shown
without this code.

[Ted C, 2017/07/21 18:45:31]

Since the controlcontainer is a child of the coordinatorlayout, why doesn't your
visibility check handle this?

It is INVISIBLE which should have it skipped.

[jaebaek, 2017/07/24 07:34:11]

You are right. I dropped this code.

+                if (offset != 0.0f && mPreviousControlOffset == 0.0f) {
+                    mControlContainer.getView().setPointerIcon(null);
+                }
+            }
         }
 
         final Tab tab = getTab();