Remove icon bg color for message center notifications.

ui/message_center/cocoa/notification_controller.mm

 // Copyright (c) 2013 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 "ui/message_center/cocoa/notification_controller.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
@@ skipping 718 matching lines @@
 
 - (NSView*)createIconView {
   // Create another box that shows a background color when the icon is not
   // big enough to fill the space.
   NSRect imageFrame = NSMakeRect(0, 0,
        message_center::kNotificationIconSize,
        message_center::kNotificationIconSize);
   base::scoped_nsobject<NSBox> imageBox(
       [[AccessibilityIgnoredBox alloc] initWithFrame:imageFrame]);
   [self configureCustomBox:imageBox];
-  [imageBox setFillColor:skia::SkColorToCalibratedNSColor(
-      message_center::kIconBackgroundColor)];
   [imageBox setAutoresizingMask:NSViewMinYMargin];
 
   // Inside the image box put the actual icon view.
   icon_.reset([[NSImageView alloc] initWithFrame:imageFrame]);
   [imageBox setContentView:icon_];
 
   return imageBox.autorelease();
 }
 
 - (NSBox*)createImageBox:(const gfx::Image&)notificationImage {
@@ skipping 231 matching lines @@
                    forFont:(NSFont*)nsfont
           maxNumberOfLines:(size_t)lines {
   size_t unused;
   return [self wrapText:text
                 forFont:nsfont
        maxNumberOfLines:lines
             actualLines:&unused];
 }
 
 @end