[Mac][Material Design] Bring bookmark hover background up to spec.

chrome/browser/ui/cocoa/gradient_button_cell.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/cocoa/gradient_button_cell.h"
 
 #include <cmath>
 
 #include "base/logging.h"
 #import "base/mac/scoped_nsobject.h"
@@ skipping 528 matching lines @@
       break;
   }
   if (type == kLeftButtonWithShadowType)
     innerFrame.size.width -= 1.0;
 
   // Return results if |return...| not null.
   if (returnInnerFrame)
     *returnInnerFrame = innerFrame;
   if (returnInnerPath) {
     DCHECK(*returnInnerPath == nil);
+    // In Material Design on Retina, nudge the hover background by 1px.
+    if ([self tag] == kMaterialStandardButtonTypeWithLimitedClickFeedback &&
+        kLineWidth < 1) {
+      drawFrame.origin.y -= kLineWidth;
+    }
+
     *returnInnerPath = [NSBezierPath bezierPathWithRoundedRect:drawFrame
                                                        xRadius:cornerRadius
                                                        yRadius:cornerRadius];
     [*returnInnerPath setLineWidth:kLineWidth];
   }
   if (returnClipPath) {
     DCHECK(*returnClipPath == nil);
     NSRect clipPathRect =
         NSInsetRect(drawFrame, -kHalfLineWidth, -kHalfLineWidth);
     *returnClipPath = [NSBezierPath
@@ skipping 269 matching lines @@
                              options:options
                                owner:self
                             userInfo:nil]);
   if (isMouseInside_ != mouseInView) {
     [self setMouseInside:mouseInView animate:NO];
     [controlView setNeedsDisplay:YES];
   }
 }
 
 @end