Implement functions to return the primary display dimensions and the number of displays connected

base/sys_info_posix.cc

Index: base/sys_info_posix.cc
===================================================================
--- base/sys_info_posix.cc	(revision 26002)
+++ base/sys_info_posix.cc	(working copy)
@@ -13,6 +13,7 @@
 #include <unistd.h>
 
 #if defined(OS_MACOSX)
+#include <ApplicationServices/ApplicationServices.h>
 #include <mach/mach_host.h>
 #include <mach/mach_init.h>
 #endif
@@ -142,13 +143,59 @@
 
 // static
 void SysInfo::GetPrimaryDisplayDimensions(int* width, int* height) {
+#if defined(OS_MACOSX)
+  CGDirectDisplayID main_display = CGMainDisplayID();
+  if (width)
+    *width = CGDisplayPixelsWide(main_display);
+  if (height)
+    *height = CGDisplayPixelsHigh(main_display);
+#else
+  // TODO(port): http://crbug.com/21732
   NOTIMPLEMENTED();
+  if (width)
+    *width = 0;
+  if (height)
+    *height = 0;
+#endif
 }
 
 // static
 int SysInfo::DisplayCount() {
+#if defined(OS_MACOSX)
+  // 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.
+      ++display_count;
+    }
+  }
+
+  return display_count;
+#else
+  // TODO(port): http://crbug.com/21732
   NOTIMPLEMENTED();
   return 1;
+#endif
 }
 
 // static