Introduce ViewRoot to forward input/view events to native

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

+// Copyright 2016 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 org.chromium.base.annotations.JNINamespace;
+
+/**
+ * Class used to forward view, input events down to native.
+ */
+@JNINamespace("ui")
+public class EventHandler {
+    private final long mNativeView;
+
+    public EventHandler(long nativeView) {
+        mNativeView = nativeView;
+    }
+
+    public void onPhysicalBackingSizeChanged(int width, int height) {
+        nativeOnPhysicalBackingSizeChanged(mNativeView, width, height);
+    }
+
+    private static native void nativeOnPhysicalBackingSizeChanged(long viewAndroid,
+            int width, int height);
+}