Implement a Menu Item to Hide the Toolbar in Fullscreen

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 2e24e1b6ff6d72849cb91e8e21a87b016e229444..5584d25d7b0742528e4cc66ce7996981ed5c761a 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller.mm
+++ b/chrome/browser/ui/cocoa/browser_window_controller.mm
@@ -1944,6 +1944,13 @@ willAnimateFromState:(BookmarkBar::State)oldState
   [self showFullscreenExitBubbleIfNecessary];
 }
 
+- (void)toggleFullscreenToolbar {
+  shouldHideFullscreenToolbar_ = !shouldHideFullscreenToolbar_;
+
+  if ([self isInAppKitFullscreen])
+    [self updateFullscreenWithToolbar:!shouldHideFullscreenToolbar_];
+}
+
 - (BOOL)isInAnyFullscreenMode {
   return [self isInImmersiveFullscreen] || [self isInAppKitFullscreen];
 }
@@ -2001,6 +2008,10 @@ willAnimateFromState:(BookmarkBar::State)oldState
              fullscreen_mac::OMNIBOX_TABS_HIDDEN;
 }
 
+- (BOOL)shouldHideFullscreenToolbar {
+  return shouldHideFullscreenToolbar_;
+}
+
 - (void)resizeFullscreenWindow {
   DCHECK([self isInAnyFullscreenMode]);
   if (![self isInAnyFullscreenMode])