Introduce ViewRoot forwarding 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 <unordered_set>
 
 #include "base/android/context_utils.h"
 #include "base/android/jni_android.h"
@@ skipping 132 matching lines @@
 
 ScopedJavaLocalRef<jobject> WindowAndroid::GetJavaObject() {
   return base::android::ScopedJavaLocalRef<jobject>(java_window_);
 }
 
 bool WindowAndroid::RegisterWindowAndroid(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 WindowAndroid::~WindowAndroid() {
-  DCHECK(parent_ == nullptr) << "WindowAndroid must be a root view.";
   DCHECK(!compositor_);
   Java_WindowAndroid_clearNativePointer(AttachCurrentThread(), GetJavaObject());
 }
 
 WindowAndroid* WindowAndroid::CreateForTesting() {
   JNIEnv* env = AttachCurrentThread();
   const JavaRef<jobject>& context = base::android::GetApplicationContext();
   long native_pointer = Java_WindowAndroid_createForTesting(env, context);
   return reinterpret_cast<WindowAndroid*>(native_pointer);
 }
@@ skipping 84 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