Add GetDisplayWithDisplayId to display::Screen.

ash/display/screen_ash_unittest.cc

Index: ash/display/screen_ash_unittest.cc
diff --git a/ash/display/screen_ash_unittest.cc b/ash/display/screen_ash_unittest.cc
index 747474f6878b7c205835bc29e34e27c0bf0625d2..6498155cd701c004ebefbe418b0c08b0005491d7 100644
--- a/ash/display/screen_ash_unittest.cc
+++ b/ash/display/screen_ash_unittest.cc
@@ -42,4 +42,17 @@ TEST_F(ScreenAshTest, TestGetWindowAtScreenPoint) {
                             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