Pass a TaskRunner through ViewsDelegate to put AX init on FILE thread

chrome/browser/ui/views/chrome_views_delegate.cc

Index: chrome/browser/ui/views/chrome_views_delegate.cc
diff --git a/chrome/browser/ui/views/chrome_views_delegate.cc b/chrome/browser/ui/views/chrome_views_delegate.cc
index 01a0585b453c120f092c3c3f5e217d82f5e15755..4e935736ee9e53190c397394b37ad79e0fbe4321 100644
--- a/chrome/browser/ui/views/chrome_views_delegate.cc
+++ b/chrome/browser/ui/views/chrome_views_delegate.cc
@@ -14,6 +14,7 @@
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/browser_window_state.h"
 #include "chrome/common/chrome_version_info.h"
+#include "content/public/browser/browser_thread.h"
 #include "content/public/browser/context_factory.h"
 #include "grit/chrome_unscaled_resources.h"
 #include "ui/base/resource/resource_bundle.h"
@@ -388,6 +389,16 @@ std::string ChromeViewsDelegate::GetApplicationName() {
   return chrome::VersionInfo().Name();
 }
 
+#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+scoped_refptr<base::TaskRunner>
+    ChromeViewsDelegate::GetTaskRunnerForAuraLinuxAccessibilityInit() {
+  // This should be on the FILE thread so that we can open libatk-bridge.so
+  // without blocking.
+  return content::BrowserThread::GetMessageLoopProxyForThread(
+      content::BrowserThread::FILE);
+}
+#endif
+
 #if defined(OS_WIN)
 int ChromeViewsDelegate::GetAppbarAutohideEdges(HMONITOR monitor,
                                                 const base::Closure& callback) {