Updates to clean up default theme and add hover states

chrome/browser/cocoa/tab_strip_view.mm

 // Copyright (c) 2009 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/cocoa/tab_strip_view.h"
 
 #include "base/logging.h"
 
 @implementation TabStripView
 
 - (id)initWithFrame:(NSRect)frame {
   self = [super initWithFrame:frame];
   if (self) {
     // Set lastMouseUp_ = -1000.0 so that timestamp-lastMouseUp_ is big unless
     // lastMouseUp_ has been reset.
     lastMouseUp_ = -1000.0;
   }
   return self;
 }
 
 - (void)drawRect:(NSRect)rect {
   NSRect boundsRect = [self bounds];
   NSRect borderRect, contentRect;
   NSDivideRect(boundsRect, &borderRect, &contentRect, 1, NSMinYEdge);
-  [[NSColor colorWithCalibratedWhite:0.0 alpha:0.3] set];
+  [[NSColor colorWithCalibratedWhite:0.0 alpha:0.2] set];
 
   NSRectFillUsingOperation(borderRect, NSCompositeSourceOver);
 }
 
 // We accept first mouse so clicks onto close/zoom/miniaturize buttons and
 // title bar double-clicks are properly detected even when the window is in the
 // background.
 - (BOOL)acceptsFirstMouse:(NSEvent*)event {
   return YES;
 }
@@ skipping 28 matching lines @@
       [[self window] performMiniaturize:self];
   } else {
     [super mouseUp:event];
   }
 
   // If clickCount is 0, the drag threshold was passed.
   lastMouseUp_ = (clickCount == 1) ? timestamp : -1000.0;
 }
 
 @end