Introduce ViewRoot forwarding input/view events to native

ui/android/view_root.h

+// Copyright 2017 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.
+
+#ifndef UI_ANDROID_VIEW_ROOT_H_
+#define UI_ANDROID_VIEW_ROOT_H_
+
+#include <jni.h>
+#include <string>
+#include <vector>
+
+#include "base/android/jni_weak_ref.h"
+#include "base/android/scoped_java_ref.h"
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "ui/android/ui_android_export.h"
+#include "ui/android/view_android.h"
+#include "ui/gfx/geometry/vector2d_f.h"
+
+namespace ui {
+
+// ViewRoot is the root of a ViewAndroid tree.
+class UI_ANDROID_EXPORT ViewRoot : public ViewAndroid {
+ public:
+  ViewRoot(WindowAndroid* window_android);

[boliu, 2017/01/04 18:58:06]

explicit

Also I don't understand why blimp is special about this. Doesn't it need a java
ViewRoot as well to forward events? Again, ViewRoot should just be a parallel
object to WindowAndroid. It's ok to hack something in blimp code, but it's not
ok that hack spills out into other code.

[Jinsuk Kim, 2017/01/05 11:03:13]

My bad - should have avoided the quick hack.

So far ViewRoot handles only physical backing size which is not needed for Blimp
(yet). The constructor can be removed.

+  ViewRoot(JNIEnv* env,
+           const base::android::JavaParamRef<jobject>& obj,
+           jlong jwindow_android);
+
+  ~ViewRoot() override;
+
+  // ViewAndroid overrides.
+  WindowAndroid* GetWindowAndroid() const override;
+  void RemoveChild(ViewAndroid* child) override;
+
+  static ViewRoot* FromJavaObject(JNIEnv* env,

[boliu, 2017/01/04 18:58:06]

style again here and below: c++ requires multi-line arguments to be lined up
vertically

[Jinsuk Kim, 2017/01/05 11:03:13]

Done.

+      const base::android::JavaParamRef<jobject>& obj);
+  void OnPhysicalBackingSizeChanged(JNIEnv* env,
+      const base::android::JavaParamRef<jobject>& jobj,
+      int width,
+      int height);
+
+ private:
+  // ViewAndroid overrides.
+  ViewAndroid* GetViewRoot() override;
+
+  JavaObjectWeakGlobalRef java_obj_;
+  WindowAndroid* window_;
+
+  DISALLOW_COPY_AND_ASSIGN(ViewRoot);
+};
+
+bool RegisterViewRoot(JNIEnv* env);
+
+}  // namespace ui
+
+#endif  // UI_ANDROID_VIEW_ROOT_H_