[NoStatePrefetch] Support only GET and HEAD

chrome/browser/prerender/prerender_resource_throttle.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/prerender/prerender_resource_throttle.h"
 
 #include "base/logging.h"
 #include "base/numerics/safe_conversions.h"
 #include "build/build_config.h"
 #include "chrome/browser/prerender/prerender_final_status.h"
@@ skipping 103 matching lines @@
     ResourceType resource_type,
     int render_process_id,
     int render_frame_id,
     const GURL& url) {
   bool cancel = false;
   PrerenderContents* prerender_contents =
       PrerenderContentsFromRenderFrame(render_process_id, render_frame_id);
   if (prerender_contents) {
     // Abort any prerenders that spawn requests that use unsupported HTTP
     // methods or schemes.
-    if (!PrerenderManager::IsValidHttpMethod(method)) {
-      prerender_contents->Destroy(FINAL_STATUS_INVALID_HTTP_METHOD);
+    if (!prerender_contents->IsValidHttpMethod(method)) {
+      // If this is a full prerender, cancel the prerender in response to
+      // invalid requests.  For prefetches, cancel invalid requests but keep the
+      // prefetch going, unless it's the main frame that's invalid.
+      if (prerender_contents->prerender_mode() == FULL_PRERENDER ||
+          resource_type == content::RESOURCE_TYPE_MAIN_FRAME) {
+        prerender_contents->Destroy(FINAL_STATUS_INVALID_HTTP_METHOD);
+      }
       cancel = true;
     } else if (!PrerenderManager::DoesSubresourceURLHaveValidScheme(url)) {
       prerender_contents->Destroy(FINAL_STATUS_UNSUPPORTED_SCHEME);
       ReportUnsupportedPrerenderScheme(url);
       cancel = true;
 #if defined(OS_ANDROID)
     } else if (resource_type == content::RESOURCE_TYPE_FAVICON) {
       // Delay icon fetching until the contents are getting swapped in
       // to conserve network usage in mobile devices.
       prerender_contents->AddResourceThrottle(throttle);
@@ skipping 83 matching lines @@
   if (g_prerender_contents_for_testing)
     return g_prerender_contents_for_testing;
   content::RenderFrameHost* rfh = content::RenderFrameHost::FromID(
       render_process_id, render_frame_id);
   content::WebContents* web_contents =
       content::WebContents::FromRenderFrameHost(rfh);
   return PrerenderContents::FromWebContents(web_contents);
 }
 
 }  // namespace prerender