mac: New asset for the tabstrip border, tweak drawing.

chrome/browser/ui/cocoa/tabs/tab_strip_view.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/tabs/tab_strip_view.h"
 
 #include <cmath>  // floor
 
 #include "base/logging.h"
 #include "base/mac/mac_util.h"
 #include "chrome/browser/themes/theme_service.h"
 #import "chrome/browser/ui/cocoa/browser_window_controller.h"
 #import "chrome/browser/ui/cocoa/new_tab_button.h"
 #import "chrome/browser/ui/cocoa/nsview_additions.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_strip_controller.h"
+#import "chrome/browser/ui/cocoa/tabs/tab_view.h"
 #import "chrome/browser/ui/cocoa/view_id_util.h"
 #include "grit/generated_resources.h"
 #include "grit/theme_resources.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"
 
 @implementation TabStripView
 
 @synthesize dropArrowShown = dropArrowShown_;
 @synthesize dropArrowPosition = dropArrowPosition_;
@@ skipping 42 matching lines @@
 
   // Draw the border bitmap, which is partially transparent.
   NSImage* image = themeProvider->GetNSImageNamed(IDR_TOOLBAR_SHADE_TOP, true);
   if (NSMinY(dirtyRect) >= [image size].height)
     return;
 
   NSRect borderRect = dirtyRect;
   borderRect.size.height = [image size].height;
   borderRect.origin.y = 0;
 
-  NSDrawThreePartImage(borderRect, nil, image, nil, /*vertical=*/NO,
-                       NSCompositeSourceOver, 1.0, /*flipped=*/NO);
+  BOOL focused = [[self window] isKeyWindow] || [[self window] isMainWindow];
+  NSDrawThreePartImage(borderRect, nil, image, nil, /*vertical=*/ NO,
+                       NSCompositeSourceOver,
+                       focused ?  1.0 : tabs::kImageNoFocusAlpha,
+                       /*flipped=*/ NO);
 }
 
 - (void)drawRect:(NSRect)rect {
   NSRect boundsRect = [self bounds];
 
   [self drawBorder:boundsRect];
 
   // Draw drop-indicator arrow (if appropriate).
   // TODO(viettrungluu): this is all a stop-gap measure.
   if ([self dropArrowShown]) {
@@ skipping 171 matching lines @@
 
 - (void)setNewTabButton:(NewTabButton*)button {
   newTabButton_.reset([button retain]);
 }
 
 - (void)setController:(TabStripController*)controller {
   controller_ = controller;
 }
 
 @end