[Mac] Fix BMB chevron button being black on Chrome open.

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm

Index: chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
diff --git a/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm b/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
index 0d5f6502b6409b9511796cc37de54cce09a1c572..174bdec82ea350604a7ce9c59baa0a9513cacd2b 100644
--- a/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
+++ b/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.mm
@@ -865,6 +865,7 @@ void RecordAppLaunch(Profile* profile, GURL url) {
   int bookmarkChildren = bookmarkModel_->bookmark_bar_node()->child_count();
   if (bookmarkChildren > displayedButtonCount_) {
     [offTheSideButton_ setHidden:NO];
+    [offTheSideButton_ setNeedsDisplay:YES];

[erikchen, 2016/01/25 14:51:05]

Does your CL still fix the problem if we only call setNeedsDisplay:  when hidden
changes from YES to NO? I'd prefer to minimize the extra redrawing that we do.

[Alexei Svitkine (slow), 2016/01/25 17:34:59]

Unfortunately, that doesn't work (on its own). The control starts visible, so
the initial time this happens the setHidden: above is a no-op.

However, I could set it to hidden in the initialization code above - i.e. after
line 429 and then the you suggest check can be added here. Would you like me to
do that?

   } else {
     // If we just deleted the last item in an off-the-side menu so the
     // button will be going away, make sure the menu goes away.