Revert to Immersive Fullscreen on OSX for a multimonitors

chrome/browser/ui/cocoa/browser_window_controller.mm

Index: chrome/browser/ui/cocoa/browser_window_controller.mm
diff --git a/chrome/browser/ui/cocoa/browser_window_controller.mm b/chrome/browser/ui/cocoa/browser_window_controller.mm
index e6616ac621bc604468998f4b4b2f16716dea9dd5..ee3cca09da91541688ea84b99310cb0c0318a6be 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller.mm
+++ b/chrome/browser/ui/cocoa/browser_window_controller.mm
@@ -2016,9 +2016,15 @@ willAnimateFromState:(BookmarkBar::State)oldState
 }
 
 - (void)enterWebContentFullscreen {
+  BOOL hasMultipleMonitors = [[NSScreen screens] count] > 1;

[Avi (use Gerrit), 2016/02/23 20:15:59]

Does this trigger with mirrored displays? Do we want it to?

[spqchan, 2016/02/23 21:27:59]

Good point on the mirrored displays. This should trigger when we have multiple
distinct displays.
Anyway, I just tested it with mirror displays and it seems to work fine.
However, I noticed that screen.h has a NumOfDisplays() method which gives you
the number of
distinct displays and decided to switch into that just to be safe.

+
   // HTML5 Fullscreen should only use AppKit fullscreen in 10.10+.
+  // However, if the user is using multiple monitors and turned off
+  // "Separate Space in Each Display", use Immersive Fullscreen so
+  // that the other monitors won't blank out.
   if (chrome::mac::SupportsSystemFullscreen() &&
-      base::mac::IsOSYosemiteOrLater())
+      base::mac::IsOSYosemiteOrLater() &&
+      !(hasMultipleMonitors && ![NSScreen screensHaveSeparateSpaces]))

[Avi (use Gerrit), 2016/02/23 20:15:59]

This if() needs {}s because the condition has multiple lines.

[spqchan, 2016/02/23 21:27:58]

Done.

     [self enterAppKitFullscreen];
   else
     [self enterImmersiveFullscreen];