Change horizontal/vertical separators in OSX bubble UI to be less light.

chrome/browser/ui/cocoa/base_bubble_controller.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.
 
 #import "chrome/browser/ui/cocoa/base_bubble_controller.h"
 
 #include "base/logging.h"
 #include "base/mac/bundle_locations.h"
 #include "base/mac/foundation_util.h"
 #include "base/mac/mac_util.h"
@@ skipping 192 matching lines @@
                               NSMaxY([parentWindow_ frame]));
   anchorOffset_.x -= anchor_.x;
   anchorOffset_.y -= anchor_.y;
 }
 
 - (NSBox*)horizontalSeparatorWithFrame:(NSRect)frame {
   frame.size.height = 1.0;
   base::scoped_nsobject<NSBox> spacer([[NSBox alloc] initWithFrame:frame]);
   [spacer setBoxType:NSBoxSeparator];
   [spacer setBorderType:NSLineBorder];
-  [spacer setAlphaValue:0.2];
+  [spacer setAlphaValue:0.75];
   return [spacer.release() autorelease];
 }
 
 - (NSBox*)verticalSeparatorWithFrame:(NSRect)frame {
   frame.size.width = 1.0;
   base::scoped_nsobject<NSBox> spacer([[NSBox alloc] initWithFrame:frame]);
   [spacer setBoxType:NSBoxSeparator];
   [spacer setBorderType:NSLineBorder];
-  [spacer setAlphaValue:0.2];
+  [spacer setAlphaValue:0.75];
   return [spacer.release() autorelease];
 }
 
 - (void)parentWindowDidResize:(NSNotification*)notification {
   if (!parentWindow_)
     return;
 
   DCHECK_EQ(parentWindow_, [notification object]);
   NSPoint newOrigin = NSMakePoint(NSMinX([parentWindow_ frame]),
                                   NSMaxY([parentWindow_ frame]));
@@ skipping 214 matching lines @@
 
 - (void)activateTabWithContents:(content::WebContents*)newContents
                previousContents:(content::WebContents*)oldContents
                         atIndex:(NSInteger)index
                          reason:(int)reason {
   // The user switched tabs; close.
   [self closeBubble];
 }
 
 @end  // BaseBubbleController