[NoStatePrefetch] Support only GET and HEAD

chrome/browser/prerender/prerender_contents.h

Index: chrome/browser/prerender/prerender_contents.h
diff --git a/chrome/browser/prerender/prerender_contents.h b/chrome/browser/prerender/prerender_contents.h
index 9e08bafe8a8b7f67f6302966b9045db5c892e9c0..996b1cc80fc9f9673fe957165ab44a1467d9437f 100644
--- a/chrome/browser/prerender/prerender_contents.h
+++ b/chrome/browser/prerender/prerender_contents.h
@@ -107,6 +107,9 @@ class PrerenderContents : public content::NotificationObserver,
   void SetPrerenderMode(PrerenderMode mode);
   PrerenderMode prerender_mode() const { return prerender_mode_; }
 
+  // Returns true iff the method given is valid for prerendering.
+  bool IsValidHttpMethod(const std::string& method);
+
   static Factory* CreateFactory();
 
   // Returns a PrerenderContents from the given web_contents, if it's used for