Hook up the SequencedWorkerPool to the browser thread.

content/public/browser/browser_thread.h

Index: content/public/browser/browser_thread.h
===================================================================
--- content/public/browser/browser_thread.h	(revision 116282)
+++ content/public/browser/browser_thread.h	(working copy)
@@ -21,6 +21,7 @@
 class MessageLoop;
 
 namespace base {
+class SequencedWorkerPool;
 class Thread;
 }
 
@@ -157,6 +158,34 @@
         from_here, object);
   }
 
+  // Simplified wrappers for posting to the blocking thread pool. Use this
+  // for doing things like blocking I/O.
+  //
+  // The first variant will run the task in the pool with no sequencing
+  // semantics, so may get run in parallel with other posted tasks. The
+  // second variant provides sequencing between tasks with the same
+  // sequence token name.
+  //
+  // These tasks are guaranteed to run before shutdown.
+  //
+  // If you need to provide different shutdown semantics (like you have
+  // something slow and noncritical that doesn't need to block shutdown),
+  // or you want to manually provide a sequence token (which saves a map
+  // lookup and is guaranteed unique without you having to come up with a
+  // unique string), you can access the sequenced worker pool directly via
+  // GetBlockingPool().
+  static bool PostBlockingPoolTask(const tracked_objects::Location& from_here,
+                                   const base::Closure& task);
+  static bool PostBlockingPoolSequencedTask(
+      const std::string& sequence_token_name,
+      const tracked_objects::Location& from_here,
+      const base::Closure& task);
+
+  // Returns the thread pool used for blocking file I/O. Use this object to
+  // perform random blocking operations such as file writes or querying the
+  // Windows registry.
+  static base::SequencedWorkerPool* GetBlockingPool();
+
   // Callable on any thread.  Returns whether the given ID corresponds to a well
   // known thread.
   static bool IsWellKnownThread(ID identifier);