Add GetDisplayWithDisplayId to display::Screen.

extensions/shell/browser/shell_screen_unittest.cc

Index: extensions/shell/browser/shell_screen_unittest.cc
diff --git a/extensions/shell/browser/shell_screen_unittest.cc b/extensions/shell/browser/shell_screen_unittest.cc
index 75a5cd161ae334b8e3719f424e96bc5b9dd87bd9..b0f3bdf643617fa2a5aaf6214a8c0d5e57cf92b7 100644
--- a/extensions/shell/browser/shell_screen_unittest.cc
+++ b/extensions/shell/browser/shell_screen_unittest.cc
@@ -26,8 +26,12 @@ TEST_F(ShellScreenTest, ShellScreen) {
   EXPECT_EQ(1, screen.GetNumDisplays());
   EXPECT_EQ(1u, screen.GetAllDisplays().size());
   EXPECT_EQ(0, screen.GetAllDisplays()[0].id());
+  display::Display display;
+  bool has_display = screen.GetDisplayWithDisplayId(0, &display);
+  EXPECT_TRUE(has_display);
+  EXPECT_EQ(0, display.id());
   EXPECT_EQ(0, screen.GetPrimaryDisplay().id());
-  EXPECT_EQ("640x480", screen.GetPrimaryDisplay().size().ToString());
+  EXPECT_EQ("640x480", display.size().ToString());
 
   // Tests that reshaping the host window reshapes the display.
   // NOTE: AuraTestBase already has its own WindowTreeHost. This is creating a