Move DisplayUtils methods into gfx::Screen.

ui/gfx/screen_mac.mm

Index: ui/gfx/screen_mac.mm
diff --git a/ui/gfx/screen_mac.mm b/ui/gfx/screen_mac.mm
index b38344ac76b85d9217aa67efbcaf663b94f08103..6bf0992896bccceb7295458bf39e3e42fe29416b 100644
--- a/ui/gfx/screen_mac.mm
+++ b/ui/gfx/screen_mac.mm
@@ -4,6 +4,7 @@
 
 #include "ui/gfx/screen.h"
 
+#import <ApplicationServices/ApplicationServices.h>
 #import <Cocoa/Cocoa.h>
 
 namespace gfx {
@@ -17,4 +18,46 @@ gfx::Point Screen::GetCursorScreenPoint() {
   return gfx::Point(mouseLocation.x, mouseLocation.y);
 }
 
+// static
+gfx::Size Screen::GetPrimaryMonitorSize() {
+  CGDirectDisplayID main_display = CGMainDisplayID();
+  return gfx::Size(CGDisplayPixelsWide(main_display),
+                   CGDisplayPixelsHigh(main_display));
+}
+
+// static
+int Screen::GetNumMonitors() {
+  // Don't just return the number of online displays.  It includes displays
+  // that mirror other displays, which are not desired in the count.  It's
+  // tempting to use the count returned by CGGetActiveDisplayList, but active
+  // displays exclude sleeping displays, and those are desired in the count.
+
+  // It would be ridiculous to have this many displays connected, but
+  // CGDirectDisplayID is just an integer, so supporting up to this many
+  // doesn't hurt.
+  CGDirectDisplayID online_displays[128];
+  CGDisplayCount online_display_count = 0;
+  if (CGGetOnlineDisplayList(arraysize(online_displays),
+                             online_displays,
+                             &online_display_count) != kCGErrorSuccess) {
+    // 1 is a reasonable assumption.
+    return 1;
+  }
+
+  int display_count = 0;
+  for (CGDisplayCount online_display_index = 0;
+       online_display_index < online_display_count;
+       ++online_display_index) {
+    CGDirectDisplayID online_display = online_displays[online_display_index];
+    if (CGDisplayMirrorsDisplay(online_display) == kCGNullDirectDisplay) {
+      // If this display doesn't mirror any other, include it in the count.
+      // The primary display in a mirrored set will be counted, but those that
+      // mirror it will not be.
+      ++display_count;
+    }
+  }
+
+  return display_count;
+}
+
 }  // namespace gfx