Introduce ViewRoot to forward input/view events to native

ui/android/window_android.cc

 // Copyright 2013 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.
 
 #include "ui/android/window_android.h"
 
 #include "base/android/context_utils.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
@@ skipping 114 matching lines @@
   for (WindowAndroidObserver& observer : observer_list_)
     observer.OnActivityStopped();
 }
 
 void WindowAndroid::OnActivityStarted(JNIEnv* env,
                                       const JavaParamRef<jobject>& obj) {
   for (WindowAndroidObserver& observer : observer_list_)
     observer.OnActivityStarted();
 }
 
+ScopedJavaLocalRef<jobject> WindowAndroid::GetViewRootForJava(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& obj) {
+  return GetViewRoot();
+}
+
 bool WindowAndroid::HasPermission(const std::string& permission) {
   JNIEnv* env = AttachCurrentThread();
   return Java_WindowAndroid_hasPermission(
       env, GetJavaObject(),
       base::android::ConvertUTF8ToJavaString(env, permission));
 }
 
 bool WindowAndroid::CanRequestPermission(const std::string& permission) {
   JNIEnv* env = AttachCurrentThread();
   return Java_WindowAndroid_canRequestPermission(
       env, GetJavaObject(),
       base::android::ConvertUTF8ToJavaString(env, permission));
 }
 
 WindowAndroid* WindowAndroid::GetWindowAndroid() const {
   DCHECK(parent_ == nullptr);
   return const_cast<WindowAndroid*>(this);
 }
 
 // ----------------------------------------------------------------------------
 // Native JNI methods
 // ----------------------------------------------------------------------------
 
 jlong Init(JNIEnv* env, const JavaParamRef<jobject>& obj, int sdk_display_id) {
   WindowAndroid* window = new WindowAndroid(env, obj, sdk_display_id);
   return reinterpret_cast<intptr_t>(window);
 }
 
 }  // namespace ui