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

content/browser/renderer_host/pepper/pepper_browser_font_singleton_host.cc

Index: content/browser/renderer_host/pepper/pepper_browser_font_singleton_host.cc
diff --git a/content/browser/renderer_host/pepper/pepper_browser_font_singleton_host.cc b/content/browser/renderer_host/pepper/pepper_browser_font_singleton_host.cc
index 02ae2a8754d1b844b813a7ab7d588099793ad1ed..99a8e04fc7031a14d9ee43509cfc326b59406d8a 100644
--- a/content/browser/renderer_host/pepper/pepper_browser_font_singleton_host.cc
+++ b/content/browser/renderer_host/pepper/pepper_browser_font_singleton_host.cc
@@ -46,9 +46,12 @@ 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(