Implement Screen::GetAllDisplays for windows.

ui/gfx/screen_win.cc

Index: ui/gfx/screen_win.cc
diff --git a/ui/gfx/screen_win.cc b/ui/gfx/screen_win.cc
index 23dbc9d60fbb865a6124b32d57690bbb41d21ba2..9bdf709d4dead4cfd40f6eea700eab203c485e57 100644
--- a/ui/gfx/screen_win.cc
+++ b/ui/gfx/screen_win.cc
@@ -29,6 +29,20 @@ gfx::Display GetDisplay(MONITORINFO& monitor_info) {
   return display;
 }
 
+BOOL CALLBACK EnumMonitorCallback(HMONITOR monitor,
+                                  HDC hdc,
+                                  LPRECT rect,
+                                  LPARAM data) {
+  std::vector<gfx::Display>* all_displays =
+      reinterpret_cast<std::vector<gfx::Display>*>(data);
+  DCHECK(all_displays);
+
+  MONITORINFO monitor_info = GetMonitorInfoForMonitor(monitor);
+  gfx::Display display = GetDisplay(monitor_info);
+  all_displays->push_back(display);
+  return TRUE;
+}
+
 }  // namespace
 
 namespace gfx {
@@ -60,8 +74,10 @@ int ScreenWin::GetNumDisplays() const {
 }
 
 std::vector<gfx::Display> ScreenWin::GetAllDisplays() const {
-  NOTIMPLEMENTED();
-  return std::vector<gfx::Display>(1, GetPrimaryDisplay());
+  std::vector<gfx::Display> all_displays;
+  EnumDisplayMonitors(NULL, NULL, EnumMonitorCallback,
+                      reinterpret_cast<LPARAM>(&all_displays));
+  return all_displays;
 }
 
 gfx::Display ScreenWin::GetDisplayNearestWindow(gfx::NativeView window) const {