Work around bug coming back from hiding menu bar with fullscreen.

base/mac/mac_util.mm

Index: base/mac/mac_util.mm
diff --git a/base/mac/mac_util.mm b/base/mac/mac_util.mm
index 35c1949fa095c58dcd7ef552dad12c0feca51695..48b4e5a190a240cfb0ec115c27cf7d4a76cf7445 100644
--- a/base/mac/mac_util.mm
+++ b/base/mac/mac_util.mm
@@ -27,6 +27,16 @@
 namespace base {
 namespace mac {
 
+// Replicate specific 10.7 SDK declarations for building with prior SDKs.
+#if !defined(MAC_OS_X_VERSION_10_7) || \
+    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
+
+enum {
+  NSApplicationPresentationFullScreen = 1 << 10
+};
+
+#endif  // MAC_OS_X_VERSION_10_7
+
 namespace {
 
 // The current count of outstanding requests for full screen mode from browser
@@ -60,6 +70,17 @@ void SetUIMode() {
                       NSApplicationPresentationHideMenuBar;
   }
 
+  // Bug-fix: if the window is fullscreened (Lion-style) and
+  // NSApplicationPresentationDefault is requested, the result is that the menu
+  // bar doesn't auto-hide. In that case, explicitly set the presentation
+  // options to the ones that are set by the system as it fullscreens a window.

[Nico, 2013/04/03 22:16:07]

file rdar

+  if (desired_options == NSApplicationPresentationDefault &&
+      current_options & NSApplicationPresentationFullScreen) {
+    desired_options |= NSApplicationPresentationFullScreen |
+                       NSApplicationPresentationAutoHideMenuBar |
+                       NSApplicationPresentationAutoHideDock;
+  }
+
   if (current_options != desired_options)
     [NSApp setPresentationOptions:desired_options];
 }