[Mac][Material Design] Add MD hover to bookmark items in menus.

chrome/browser/ui/cocoa/gradient_button_cell.h

Index: chrome/browser/ui/cocoa/gradient_button_cell.h
diff --git a/chrome/browser/ui/cocoa/gradient_button_cell.h b/chrome/browser/ui/cocoa/gradient_button_cell.h
index d635d4218c278eb3b0fbdde59c18751b811e5f5d..1c798eab8f145b0d36e6b76c588089326064160b 100644
--- a/chrome/browser/ui/cocoa/gradient_button_cell.h
+++ b/chrome/browser/ui/cocoa/gradient_button_cell.h
@@ -114,6 +114,10 @@ typedef enum {
 // be overriden by objects that inherit this class for placement of text.
 - (int)verticalTextOffset;
 
+// The amount by which the gradient button cell should nudge the path used to
+// draw the hover (and pressed) state background path.
+- (CGFloat)hoverBackgroundVerticalOffsetInControlView:(NSView*)controlView;
+
 @property(assign, nonatomic) CGFloat hoverAlpha;
 
 // An image that will be drawn after the normal content of the button cell,