Add GetDisplayWithDisplayId to display::Screen.

ash/display/screen_ash_unittest.cc

 // Copyright 2015 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 "ash/display/display_manager.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
 #include "ui/aura/test/test_window_delegate.h"
 #include "ui/aura/window.h"
 
@@ skipping 24 matching lines @@
       &delegate, 1, gfx::Rect(200, 200, 100, 100)));
 
   ASSERT_NE(win1->GetRootWindow(), win2->GetRootWindow());
 
   EXPECT_EQ(win1.get(), display::Screen::GetScreen()->GetWindowAtScreenPoint(
                             gfx::Point(50, 60)));
   EXPECT_EQ(win2.get(), display::Screen::GetScreen()->GetWindowAtScreenPoint(
                             gfx::Point(250, 260)));
 }
 
+TEST_F(ScreenAshTest, TestGetDisplayById) {
+  if (!SupportsMultipleDisplays())
+    return;
+
+  UpdateDisplay("200x200,400x400");
+  int64_t id = SetFirstDisplayAsInternalDisplay();
+  display::Display display;
+  bool has_display =
+      display::Screen::GetScreen()->GetDisplayWithDisplayId(id, &display);
+  EXPECT_TRUE(has_display);
+  EXPECT_EQ(id, display.id());
+}
+
 }  // namespace ash