Mac: Don't perform unnecessary star decoration redraws.

If the star in the Location Bar is already in the correct state, then there's
no need to perform a complete redraw.

This was responsible for ~50% of extraneous location bar redraws, which was
consuming ~5% of cpu cycles on start up.

BUG=393819

Review URL: https://codereview.chromium.org/442343006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287902 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/cocoa/location_bar/location_bar_view_mac.mm

@@ -339,6 +339,9 @@ bool LocationBarViewMac::IsEditable() {
 }
 
 void LocationBarViewMac::SetStarred(bool starred) {
+  if (star_decoration_->starred() == starred)
+    return;
+
   star_decoration_->SetStarred(starred);
   UpdateStarDecorationVisibility();
   OnDecorationsChanged();