MacViews: Implement Tab Dragging

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 6fb7c6e8dc284f597a9f5cac0b9966d085968b97..c6de34f4bf572e1c1ad7019cc82b0613f0cb0fe0 100644
--- a/ui/gfx/screen_mac.mm
+++ b/ui/gfx/screen_mac.mm
@@ -16,6 +16,7 @@
 #include "base/timer/timer.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/display_change_notifier.h"
+#include "ui/gfx/mac/coordinate_conversion.h"
 
 namespace {
 
@@ -24,13 +25,7 @@ namespace {
 const int64_t kConfigureDelayMs = 500;
 
 gfx::Rect ConvertCoordinateSystem(NSRect ns_rect) {
-  // Primary monitor is defined as the monitor with the menubar,
-  // which is always at index 0.
-  NSScreen* primary_screen = [[NSScreen screens] firstObject];
-  float primary_screen_height = [primary_screen frame].size.height;
-  gfx::Rect rect(NSRectToCGRect(ns_rect));
-  rect.set_y(primary_screen_height - rect.y() - rect.height());
-  return rect;
+  return gfx::ScreenRectFromNSRect(ns_rect);
 }
 
 NSScreen* GetMatchingScreen(const gfx::Rect& match_rect) {
@@ -105,9 +100,7 @@ class ScreenMac : public gfx::Screen {
   gfx::Point GetCursorScreenPoint() override {
     NSPoint mouseLocation  = [NSEvent mouseLocation];
     // Flip coordinates to gfx (0,0 in top-left corner) using primary screen.
-    NSScreen* screen = [[NSScreen screens] firstObject];
-    mouseLocation.y = NSMaxY([screen frame]) - mouseLocation.y;
-    return gfx::Point(mouseLocation.x, mouseLocation.y);
+    return gfx::ScreenPointFromNSPoint(mouseLocation);
   }
 
   gfx::NativeWindow GetWindowUnderCursor() override {