Always call the class methods to save/restore contexts.

chrome/default_plugin/plugin_impl_mac.mm

Index: chrome/default_plugin/plugin_impl_mac.mm
diff --git a/chrome/default_plugin/plugin_impl_mac.mm b/chrome/default_plugin/plugin_impl_mac.mm
index eb0ee08e711d3f92541e02df7b24de1aab43a223..b6deb280604a019a7d1bb8af9baecea5ed231825 100644
--- a/chrome/default_plugin/plugin_impl_mac.mm
+++ b/chrome/default_plugin/plugin_impl_mac.mm
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -17,6 +17,7 @@
 #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"
@@ -139,7 +140,7 @@ void PluginInstallerImpl::DownloadCancelled() {
 }
 
 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];
@@ -183,7 +184,6 @@ int16 PluginInstallerImpl::OnDrawRect(CGContextRef context, CGRect dirty_rect) {
   label_point = NSMakePoint(roundf(label_point.x), roundf(label_point.y));
   [command_ drawAtPoint:label_point withAttributes:attributes];
 
-  [NSGraphicsContext restoreGraphicsState];
   return 1;
 }