Add and use gfx::ScopedNSGraphicsContextState (ui/gfx/scoped_ns_graphics_context_state_mac.h).

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_toolbar_view.mm

 // Copyright (c) 2011 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/bookmarks/bookmark_bar_toolbar_view.h"
 
 #include "chrome/browser/ntp_background_util.h"
 #include "chrome/browser/themes/theme_service.h"
 #import "chrome/browser/ui/cocoa/bookmarks/bookmark_bar_constants.h"
 #import "chrome/browser/ui/cocoa/bookmarks/bookmark_bar_controller.h"
 #import "chrome/browser/ui/cocoa/browser_window_controller.h"
 #import "chrome/browser/ui/cocoa/themed_window.h"
 #include "ui/base/theme_provider.h"
 #include "ui/gfx/canvas_skia_paint.h"
 #include "ui/gfx/rect.h"
+#include "ui/gfx/scoped_ns_graphics_context_state_mac.h"
 
 const CGFloat kBorderRadius = 3.0;
 
 @interface BookmarkBarToolbarView (Private)
 - (void)drawRectAsBubble:(NSRect)rect;
 @end
 
 @implementation BookmarkBarToolbarView
 
 - (BOOL)isOpaque {
@@ skipping 23 matching lines @@
   // to morph the bubble to a regular bar (shape and colour).
   CGFloat morph = [controller_ detachedMorphProgress];
 
   NSRect bounds = [self bounds];
 
   ui::ThemeProvider* themeProvider = [controller_ themeProvider];
   if (!themeProvider)
     return;
 
   NSGraphicsContext* context = [NSGraphicsContext currentContext];
-  [context saveGraphicsState];
+  gfx::ScopedNSGraphicsContextState scopedGState(context);
 
   // Draw the background.
   {
     // CanvasSkiaPaint draws to the NSGraphicsContext during its destructor, so
     // explicitly scope this.
     //
     // Paint the entire bookmark bar, even if the damage rect is much smaller
     // because PaintBackgroundDetachedMode() assumes that area's origin is
     // (0, 0) and that its size is the size of the bookmark bar.
     //
@@ skipping 24 matching lines @@
                                       yRadius:(morph * kBorderRadius)];
 
   // Draw the rounded rectangle.
   NSColor* toolbarColor =
       themeProvider->GetNSColor(ThemeService::COLOR_TOOLBAR, true);
   CGFloat alpha = morph * [toolbarColor alphaComponent];
   [[toolbarColor colorWithAlphaComponent:alpha] set];  // Set with opacity.
   [border fill];
 
   // Fade in/out the background.
-  [context saveGraphicsState];
-  [border setClip];
-  CGContextRef cgContext = (CGContextRef)[context graphicsPort];
-  CGContextBeginTransparencyLayer(cgContext, NULL);
-  CGContextSetAlpha(cgContext, 1 - morph);
-  [context setPatternPhase:[[self window] themePatternPhase]];
-  [self drawBackground];
-  CGContextEndTransparencyLayer(cgContext);
-  [context restoreGraphicsState];
+  {
+    gfx::ScopedNSGraphicsContextState bgScopedState(context);
+    [border setClip];
+    CGContextRef cgContext = (CGContextRef)[context graphicsPort];
+    CGContextBeginTransparencyLayer(cgContext, NULL);
+    CGContextSetAlpha(cgContext, 1 - morph);
+    [context setPatternPhase:[[self window] themePatternPhase]];
+    [self drawBackground];
+    CGContextEndTransparencyLayer(cgContext);
+  }
 
   // Draw the border of the rounded rectangle.
   NSColor* borderColor = themeProvider->GetNSColor(
       ThemeService::COLOR_TOOLBAR_BUTTON_STROKE, true);
   alpha = morph * [borderColor alphaComponent];
   [[borderColor colorWithAlphaComponent:alpha] set];  // Set with opacity.
   [border stroke];
 
   // Fade in/out the divider.
   // TODO(viettrungluu): It's not obvious that this divider lines up exactly
   // with |BackgroundGradientView|'s (in fact, it probably doesn't).
   NSColor* strokeColor = [self strokeColor];
   alpha = (1 - morph) * [strokeColor alphaComponent];
   [[strokeColor colorWithAlphaComponent:alpha] set];
   NSBezierPath* divider = [NSBezierPath bezierPath];
   NSPoint dividerStart =
       NSMakePoint(morph * bookmarks::kNTPBookmarkBarPadding + morph * 0.5,
                   morph * bookmarks::kNTPBookmarkBarPadding + morph * 0.5);
   CGFloat dividerWidth =
       NSWidth(bounds) - 2 * morph * bookmarks::kNTPBookmarkBarPadding - 2 * 0.5;
   [divider moveToPoint:dividerStart];
   [divider relativeLineToPoint:NSMakePoint(dividerWidth, 0)];
   [divider stroke];
-
-  // Restore the graphics context.
-  [context restoreGraphicsState];
 }
 
 @end  // @implementation BookmarkBarToolbarView