Introduce ViewRoot to forward input/view events to native

ui/android/java/src/org/chromium/ui/base/WindowAndroid.java

 // Copyright 2012 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.ui.base;
 
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
@@ skipping 91 matching lines @@
     private final AccessibilityManager mAccessibilityManager;
 
     // Whether touch exploration is enabled.
     private boolean mIsTouchExplorationEnabled;
 
     // On KitKat and higher, a class that monitors the touch exploration state.
     private TouchExplorationMonitor mTouchExplorationMonitor;
 
     private AndroidPermissionDelegate mPermissionDelegate;
 
+    private EventHandler mEventHandler;
+
     /**
      * An interface to notify listeners of changes in the soft keyboard's visibility.
      */
     public interface KeyboardVisibilityListener {
         public void keyboardVisibilityChanged(boolean isShowing);
     }
     private LinkedList<KeyboardVisibilityListener> mKeyboardVisibilityListeners =
             new LinkedList<>();
 
     private final VSyncMonitor.Listener mVSyncListener = new VSyncMonitor.Listener() {
@@ skipping 558 matching lines @@
      * setWillNotDraw(false) to ensure that the animation is drawn over the SurfaceView,
      * and otherwise we call setWillNotDraw(true).
      */
     private void refreshWillNotDraw() {
         boolean willNotDraw = !mIsTouchExplorationEnabled && mAnimationsOverContent.isEmpty();
         if (mAnimationPlaceholderView.willNotDraw() != willNotDraw) {
             mAnimationPlaceholderView.setWillNotDraw(willNotDraw);
         }
     }
 
+    /**
+     * @return {@link EventHandler} instance used to forward input/view events down to native.
+     */
+    public EventHandler getEventHandler() {
+        if (mEventHandler == null) {
+            mEventHandler = nativeGetEventHandler(mNativeWindowAndroid);
+        }
+        return mEventHandler;
+    }
+
+    @CalledByNative
+    private EventHandler createEventHandler(long nativeView) {
+        return new EventHandler(nativeView);
+    }
+
     private native long nativeInit(int displayId);
     private native void nativeOnVSync(long nativeWindowAndroid,
                                       long vsyncTimeMicros,
                                       long vsyncPeriodMicros);
     private native void nativeOnVisibilityChanged(long nativeWindowAndroid, boolean visible);
     private native void nativeOnActivityStopped(long nativeWindowAndroid);
     private native void nativeOnActivityStarted(long nativeWindowAndroid);
     private native void nativeDestroy(long nativeWindowAndroid);
-
+    private native EventHandler nativeGetEventHandler(long nativeWindowAndroid);
 }