ThreadChecker instead of SequenceChecker in classes that use TLS.

content/child/fileapi/webfilesystem_impl.h

Index: content/child/fileapi/webfilesystem_impl.h
diff --git a/content/child/fileapi/webfilesystem_impl.h b/content/child/fileapi/webfilesystem_impl.h
index 4efe2f9463a0b5da06b0b431a342a2da0fd205a1..133becd205cc7ea392b1cb99170ed24e3457e51e 100644
--- a/content/child/fileapi/webfilesystem_impl.h
+++ b/content/child/fileapi/webfilesystem_impl.h
@@ -10,7 +10,7 @@
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/sequence_checker.h"
+#include "base/threading/thread_checker.h"
 #include "content/public/child/worker_thread.h"
 #include "third_party/WebKit/public/platform/WebFileSystem.h"
 
@@ -106,7 +106,8 @@ class WebFileSystemImpl : public blink::WebFileSystem,
   int next_callbacks_id_;
   WaitableCallbackResultsMap waitable_results_;
 
-  SEQUENCE_CHECKER(sequence_checker_);
+  // Thread-affine per use of TLS in impl.
+  THREAD_CHECKER(thread_checker_);
 
   DISALLOW_COPY_AND_ASSIGN(WebFileSystemImpl);
 };