Fix the misalignment on CrOS of the tab background images

chrome/browser/ui/cocoa/themed_window.h

 // Copyright (c) 2010 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.
 
 #ifndef CHROME_BROWSER_UI_COCOA_THEMED_WINDOW_H_
 #define CHROME_BROWSER_UI_COCOA_THEMED_WINDOW_H_
 
 #import <Cocoa/Cocoa.h>
 
 namespace ui {
 class ThemeProvider;
 }
 using ui::ThemeProvider;
 
 // Bit flags; mix-and-match as necessary.
 enum {
   THEMED_NORMAL    = 0,
   THEMED_INCOGNITO = 1 << 0,
   THEMED_POPUP     = 1 << 1,
   THEMED_DEVTOOLS  = 1 << 2
 };
 typedef NSUInteger ThemedWindowStyle;
 
 // Indicates how the theme image should be aligned.
 enum ThemeImageAlignment {
   // Aligns the top of the theme image with the top of the frame. Use this
-  // for IDR_THEME_THEME_FRAME.*
+  // for IDR_THEME_THEME_FRAME.* and IDR_THEME_TAB_BACKGROUND.
   THEME_IMAGE_ALIGN_WITH_FRAME,
   // Aligns the top of the theme image with the top of the tabs.
-  // Use this for IDR_THEME_TAB_BACKGROUND and IDR_THEME_TOOLBAR.
+  // Use this for IDR_THEME_TAB_BACKGROUND_OVERLAY,
+  // IDR_THEME_TAB_BACKGROUND_INACTIVE, and IDR_THEME_TOOLBAR.
   THEME_IMAGE_ALIGN_WITH_TAB_STRIP
 };
 
 // Implemented by windows that support theming.
 
 @interface NSWindow (ThemeProvider)
 - (ThemeProvider*)themeProvider;
 - (ThemedWindowStyle)themedWindowStyle;
 
 // Returns the position in the coordinates of the root view
 // ([[self contentView] superview]) that the top left of a theme image with
 // |alignment| should be painted at. The result of this method can be used in
 // conjunction with [NSGraphicsContext cr_setPatternPhase:] to set the offset of
 // pattern colors.
 - (NSPoint)themeImagePositionForAlignment:(ThemeImageAlignment)alignment;
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_THEMED_WINDOW_H_