Introduce ViewRoot forwarding input/view events to native

ui/snapshot/snapshot_android.cc

 // Copyright (c) 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.
 
 #include "ui/snapshot/snapshot.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 24 matching lines @@
   return false;
 }
 
 static void MakeAsyncCopyRequest(
     gfx::NativeWindow window,
     const gfx::Rect& source_rect,
     const cc::CopyOutputRequest::CopyOutputRequestCallback& callback) {
   std::unique_ptr<cc::CopyOutputRequest> request =
       cc::CopyOutputRequest::CreateBitmapRequest(callback);
 
+  ViewAndroid view;
+  view.SetWindowAndroid(window);

[boliu, 2017/01/03 19:16:11]

err, this is just wrong..

This code can talk to DisplayAndroidManager directly, so maybe should do that.

So add a DisplayAndroidManager::GetInstance method, which can get the screen and
just downcast it. Then add a method to DisplayAndroidManager that just takes a
WindowAndroid.

This does beg the question, long term, should gfx::NativeWindow be redefined to
ViewRoot. I'm not sure what the answer is though.. whatever is convenient I
guess.

[Jinsuk Kim, 2017/01/04 10:45:02]

I have a problem getting this to build(undefined reference to
'ui::DisplayAndroidManager::GetDisplayNearestWindowAndroid(ui::WindowAndroid*)
const'). Will fix this soon.

[boliu, 2017/01/04 18:58:05]

Need to add UI_ANDROID_EXPORT to DisplayAndroidManager

[Jinsuk Kim, 2017/01/05 11:03:12]

Ah

+
   const display::Display& display =
-      display::Screen::GetScreen()->GetDisplayNearestWindow(window);
+      display::Screen::GetScreen()->GetDisplayNearestWindow(&view);
   float device_scale_factor = display.device_scale_factor();
   gfx::Rect source_rect_in_pixel =
       gfx::ScaleToEnclosingRect(source_rect, device_scale_factor);
 
   // Account for the toolbar offset.
   gfx::Vector2dF offset_in_pixel =
       gfx::ScaleVector2d(window->content_offset(), device_scale_factor);
   gfx::Rect adjusted_source_rect(
       gfx::ToRoundedPoint(
           gfx::PointF(source_rect_in_pixel.x() + offset_in_pixel.x(),
@@ skipping 33 matching lines @@
 void GrabViewSnapshotAsync(
     gfx::NativeView view,
     const gfx::Rect& source_rect,
     scoped_refptr<base::TaskRunner> background_task_runner,
     const GrabWindowSnapshotAsyncPNGCallback& callback) {
   GrabWindowSnapshotAsync(
       view->GetWindowAndroid(), source_rect, background_task_runner, callback);
 }
 
 }  // namespace ui