Always call the class methods to save/restore contexts.

chrome/default_plugin/plugin_impl_mac.mm

 // 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.
 
 #include "chrome/default_plugin/plugin_impl_mac.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/file_util.h"
 #include "base/path_service.h"
 #include "base/string_util.h"
 #include "chrome/default_plugin/plugin_main.h"
 #include "googleurl/src/gurl.h"
 #include "grit/default_plugin_resources.h"
 #include "grit/webkit_strings.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/image/image.h"
+#include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"
 #include "unicode/locid.h"
 #include "webkit/glue/webkit_glue.h"
 #include "webkit/plugins/npapi/default_plugin_shared.h"
 
 // TODO(thakis): Most methods in this class are stubbed out and need to be
 // implemented.
 
 PluginInstallerImpl::PluginInstallerImpl(int16 mode)
     : image_(nil),
       command_(nil) {
@@ skipping 102 matching lines @@
 }
 
 void PluginInstallerImpl::DownloadPlugin() {
 }
 
 void PluginInstallerImpl::DownloadCancelled() {
   DisplayAvailablePluginStatus();
 }
 
 int16 PluginInstallerImpl::OnDrawRect(CGContextRef context, CGRect dirty_rect) {
-  [NSGraphicsContext saveGraphicsState];
+  gfx::ScopedNSGraphicsContextSaveGState scoped_state;
   NSGraphicsContext* ns_context = [NSGraphicsContext
       graphicsContextWithGraphicsPort:context flipped:YES];
   [NSGraphicsContext setCurrentContext:ns_context];

[Mark Mentovai, 2011/08/05 01:15:45]

☞

 
   // Fill background.
   NSColor* bg_color = [NSColor colorWithCalibratedRed:252 / 255.0
                                                 green:235 / 255.0
                                                  blue:162 / 255.0
                                                 alpha:1.0];
   [bg_color setFill];
   NSRectFill(NSRectFromCGRect(dirty_rect));
 
   [[NSColor blackColor] set];
@@ skipping 20 matching lines @@
       nil];
 
   NSSize text_size = [command_ sizeWithAttributes:attributes];
   NSPoint label_point = NSMakePoint((width_ - text_size.width) / 2,
                                     (height_ - text_size.height) / 2);
   if (image_)
     label_point.y += [image_ size].height / 2 + text_size.height / 2 + 10;
   label_point = NSMakePoint(roundf(label_point.x), roundf(label_point.y));
   [command_ drawAtPoint:label_point withAttributes:attributes];
 
-  [NSGraphicsContext restoreGraphicsState];
   return 1;
 }
 
 
 void PluginInstallerImpl::ShowInstallDialog() {
 }
 
 void PluginInstallerImpl::NotifyPluginStatus(int status) {
   default_plugin::g_browser->getvalue(
       instance_,
       static_cast<NPNVariable>(
           webkit::npapi::default_plugin::kMissingPluginStatusStart + status),
       NULL);
 }