Reland of Android: support multiple displays on C++ side

ui/android/dummy_screen_android.cc

+// 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.
+
+#include "ui/android/screen_android.h"
+#include "ui/display/display.h"
+#include "ui/display/screen.h"
+
+namespace ui {
+
+using display::Display;
+using display::DisplayObserver;
+
+class DummyScreenAndroid : public display::Screen {
+ public:
+  DummyScreenAndroid() {}
+  ~DummyScreenAndroid() override {}
+
+  // Screen interface.
+
+  gfx::Point GetCursorScreenPoint() override { return gfx::Point(); }
+
+  bool IsWindowUnderCursor(gfx::NativeWindow window) override { return false; }
+
+  gfx::NativeWindow GetWindowAtScreenPoint(const gfx::Point& point) override {
+    return NULL;
+  }
+
+  int GetNumDisplays() const override { return 1; }
+
+  std::vector<Display> GetAllDisplays() const override {
+    return std::vector<Display>(1, GetPrimaryDisplay());
+  }
+
+  Display GetDisplayNearestWindow(gfx::NativeView view) const override {
+    return GetPrimaryDisplay();
+  }
+
+  Display GetDisplayNearestPoint(const gfx::Point& point) const override {
+    return GetPrimaryDisplay();
+  }
+
+  Display GetDisplayMatching(const gfx::Rect& match_rect) const override {
+    return GetPrimaryDisplay();
+  }
+
+  Display GetPrimaryDisplay() const override {
+    const int display_id = 0;
+    const gfx::Rect bounds_in_dip(256, 512);
+    return display::Display(display_id, bounds_in_dip);
+  }
+
+  void AddObserver(DisplayObserver* observer) override {}
+  void RemoveObserver(DisplayObserver* observer) override {}
+};
+
+display::Screen* CreateScreenAndroidForTests() {
+  return new DummyScreenAndroid;
+}
+
+}  // namespace ui