Revert of [Prerender] Restore request priorities when swapped in

chrome/browser/prerender/prerender_resource_throttle.h

Index: chrome/browser/prerender/prerender_resource_throttle.h
diff --git a/chrome/browser/prerender/prerender_resource_throttle.h b/chrome/browser/prerender/prerender_resource_throttle.h
index 0302ec5e710298dafae4a28e357071045579c303..a9f853ec9ccb45379d74940b614b10688629d6d5 100644
--- a/chrome/browser/prerender/prerender_resource_throttle.h
+++ b/chrome/browser/prerender/prerender_resource_throttle.h
@@ -10,12 +10,10 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
-#include "base/optional.h"
 #include "chrome/common/prerender_types.h"
 #include "content/public/browser/resource_request_info.h"
 #include "content/public/browser/resource_throttle.h"
 #include "content/public/common/resource_type.h"
-#include "net/base/request_priority.h"
 
 class GURL;
 
@@ -51,9 +49,6 @@
   // Called by the PrerenderContents when a prerender becomes visible.
   // May only be called if currently throttling the resource.
   void ResumeHandler();
-
-  // Resets the resource priority back to its original value.
-  void ResetResourcePriority();
 
   static void OverridePrerenderContentsForTesting(PrerenderContents* contents);
 
@@ -95,11 +90,6 @@
   net::URLRequest* request_;
   int load_flags_;  // Load flags to be OR'ed with the existing request flags.
 
-  // The throttle changes most request priorities to IDLE during prerendering.
-  // The priority is reset back to the original priority when prerendering is
-  // finished.
-  base::Optional<net::RequestPriority> original_request_priority_;
-
   scoped_refptr<PrerenderThrottleInfo> prerender_throttle_info_;
 
   DISALLOW_COPY_AND_ASSIGN(PrerenderResourceThrottle);