Use sequenced workers for the getting the system's font list.

content/browser/renderer_host/pepper/pepper_browser_font_singleton_host.cc

 // Copyright (c) 2012 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 "content/browser/renderer_host/pepper/pepper_browser_font_singleton_host.h"
 
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/values.h"
 #include "content/common/font_list.h"
 #include "content/public/browser/browser_ppapi_host.h"
@@ skipping 28 matching lines @@
 };
 
 FontMessageFilter::FontMessageFilter() {
 }
 
 FontMessageFilter::~FontMessageFilter() {
 }
 
 scoped_refptr<base::TaskRunner> FontMessageFilter::OverrideTaskRunnerForMessage(
     const IPC::Message& msg) {
-  // Use the blocking pool to get the font list (currently the only message
-  // so we can always just return it).
-  return scoped_refptr<base::TaskRunner>(BrowserThread::GetBlockingPool());
+  // Use the blocking pool to get the font list (currently the only message)
+  // Since getting the font list is non-threadsafe on Linux (for versions of
+  // Pango predating 2013), use a sequenced task runner.
+  base::SequencedWorkerPool* pool = BrowserThread::GetBlockingPool();
+  return pool->GetSequencedTaskRunner(
+      pool->GetNamedSequenceToken(kFontListSequenceToken));
 }
 
 int32_t FontMessageFilter::OnResourceMessageReceived(
     const IPC::Message& msg,
     ppapi::host::HostMessageContext* context) {
   IPC_BEGIN_MESSAGE_MAP(FontMessageFilter, msg)
     PPAPI_DISPATCH_HOST_RESOURCE_CALL_0(
         PpapiHostMsg_BrowserFontSingleton_GetFontFamilies,
         OnHostMsgGetFontFamilies)
   IPC_END_MESSAGE_MAP()
@@ skipping 37 matching lines @@
     PP_Resource resource)
     : ResourceHost(host->GetPpapiHost(), instance, resource) {
   AddFilter(scoped_refptr<ppapi::host::ResourceMessageFilter>(
       new FontMessageFilter()));
 }
 
 PepperBrowserFontSingletonHost::~PepperBrowserFontSingletonHost() {
 }
 
 }  // namespace content