Reduce/remove usage of BrowserThread in content/browser/loader.

content/browser/loader/resource_loader.h

Index: content/browser/loader/resource_loader.h
diff --git a/content/browser/loader/resource_loader.h b/content/browser/loader/resource_loader.h
index ce610e0a902ca19c6c01ee4651021753d9249178..9558c19d766dd7eba14926851d7d9e083897684f 100644
--- a/content/browser/loader/resource_loader.h
+++ b/content/browser/loader/resource_loader.h
@@ -10,6 +10,7 @@
 #include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "content/browser/loader/resource_controller.h"
 #include "content/browser/loader/resource_handler.h"
@@ -176,6 +177,8 @@ class CONTENT_EXPORT ResourceLoader : public net::URLRequest::Delegate,
   scoped_refptr<net::IOBuffer> read_buffer_;
   int read_buffer_size_;
 
+  base::ThreadChecker thread_checker_;
+
   base::WeakPtrFactory<ResourceLoader> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ResourceLoader);