[Mac] Increase contrast of toolbar button hover bg in MD Incognito.

chrome/browser/ui/cocoa/toolbar/toolbar_button_cocoa.mm

 // Copyright (c) 2011 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.
 
 #import "chrome/browser/ui/cocoa/toolbar/toolbar_button_cocoa.h"
 
 #include "base/mac/foundation_util.h"
 #include "base/mac/sdk_forward_declarations.h"
 #import "chrome/browser/ui/cocoa/image_button_cell.h"
 #import "chrome/browser/ui/cocoa/view_id_util.h"
@@ skipping 72 matching lines @@
   NSBezierPath* roundedRectPath =
       [NSBezierPath bezierPathWithRoundedRect:destRect xRadius:2 yRadius:2];
 
   // Determine the fill color.
   NSColor* fillColor = nil;
   switch (imageRep.style) {
     case ToolbarButtonImageBackgroundStyle::HOVER:
       fillColor = [NSColor colorWithCalibratedWhite:0 alpha:0.08];
       break;
     case ToolbarButtonImageBackgroundStyle::HOVER_THEMED:
-      fillColor = [NSColor colorWithCalibratedWhite:1 alpha:0.08];
+      fillColor = [NSColor colorWithCalibratedWhite:1 alpha:0.12];
       break;
     case ToolbarButtonImageBackgroundStyle::PRESSED:
       fillColor = [NSColor colorWithCalibratedWhite:0 alpha:0.12];
       break;
     case ToolbarButtonImageBackgroundStyle::PRESSED_THEMED:
-      fillColor = [NSColor colorWithCalibratedWhite:1 alpha:0.12];
+      fillColor = [NSColor colorWithCalibratedWhite:1 alpha:0.16];
       break;
   }
 
   // Fill the path.
   [fillColor set];
   [roundedRectPath fill];
 
   // Center the icon within the button.
   NSSize iconSize = [imageRep.icon size];
   CGFloat iconInset = (kMDButtonBounds.size.width - iconSize.width) / 2;
@@ skipping 241 matching lines @@
   // Update the hover and pressed image backgrounds to match the current theme.
   if (ui::MaterialDesignController::IsModeMaterial()) {
     [self resetButtonStateImages];
   }
 }
 
 - (void)windowDidChangeActive {
 }
 
 @end