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 top of the theme image should be aligned.
+enum ThemePatternAlignment {
+  THEME_PATTERN_ALIGN_WITH_FRAME,
+  THEME_PATTERN_ALIGN_WITH_TAB_STRIP

[Nico, 2013/07/17 18:03:04]

Add comments explaining what these do and when to use which.

+};
+
 // Implemented by windows that support theming.
 
 @interface NSWindow (ThemeProvider)
 - (ThemeProvider*)themeProvider;
 - (ThemedWindowStyle)themedWindowStyle;
-- (NSPoint)themePatternPhase;
+- (NSPoint)themePatternPhaseForAlignment:(ThemePatternAlignment)alignment;
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_THEMED_WINDOW_H_