Improve console log message for CORS failure

Source/core/loader/DocumentThreadableLoader.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 281 matching lines @@
         --m_corsRedirectLimit;
 
         InspectorInstrumentation::didReceiveCORSRedirectResponse(m_document.frame(), resource->identifier(), m_document.frame()->loader().documentLoader(), redirectResponse, 0);
 
         bool allowRedirect = false;
         String accessControlErrorDescription;
 
         // Non-simple cross origin requests (both preflight and actual one) are
         // not allowed to follow redirect.
         if (m_crossOriginNonSimpleRequest) {
-            accessControlErrorDescription = "The request was redirected to '"+ request.url().string() + "', which is disallowed for cross-origin requests that require preflight.";
+            accessControlErrorDescription = "The request was redirected to '" + request.url().string() + "', which is disallowed for cross-origin requests that require preflight.";
         } else {
             // The redirect response must pass the access control check if the
             // original request was not same-origin.
-            allowRedirect = CrossOriginAccessControl::isLegalRedirectLocation(request.url(), accessControlErrorDescription)
-                && (m_sameOriginRequest || passesAccessControlCheck(redirectResponse, effectiveAllowCredentials(), securityOrigin(), accessControlErrorDescription));
+            if (CrossOriginAccessControl::isLegalRedirectLocation(request.url(), accessControlErrorDescription)) {
+                if (m_sameOriginRequest || passesAccessControlCheck(redirectResponse, effectiveAllowCredentials(), securityOrigin(), accessControlErrorDescription)) {
+                    allowRedirect = true;
+                } else {
+                    accessControlErrorDescription = "The request was redirected to '" + request.url().string() + "', and has been blocked from loading by Cross-Origin Resource Sharing policy: " + accessControlErrorDescription;
+                }
+            }
         }
 
         if (allowRedirect) {
             // FIXME: consider combining this with CORS redirect handling performed by
             // CrossOriginAccessControl::handleRedirect().
             clearResource();
 
             RefPtr<SecurityOrigin> originalOrigin = SecurityOrigin::create(redirectResponse.url());
             RefPtr<SecurityOrigin> requestOrigin = SecurityOrigin::create(request.url());
             // If the original request wasn't same-origin, then if the request URL origin is not same origin with the original URL origin,
@@ skipping 69 matching lines @@
         m_isUsingDataConsumerHandle = true;
 
     handleResponse(resource->identifier(), response, handle);
 }
 
 void DocumentThreadableLoader::handlePreflightResponse(const ResourceResponse& response)
 {
     String accessControlErrorDescription;
 
     if (!passesAccessControlCheck(response, effectiveAllowCredentials(), securityOrigin(), accessControlErrorDescription)) {
-        handlePreflightFailure(response.url().string(), accessControlErrorDescription);
+        handlePreflightFailure(response.url().string(), "Response for preflight doesn't pass the access control check: " + accessControlErrorDescription);
         return;
     }
 
     if (!passesPreflightStatusCheck(response, accessControlErrorDescription)) {
         handlePreflightFailure(response.url().string(), accessControlErrorDescription);
         return;
     }
 
     OwnPtr<CrossOriginPreflightResultCacheItem> preflightResult = adoptPtr(new CrossOriginPreflightResultCacheItem(effectiveAllowCredentials()));
     if (!preflightResult->parse(response, accessControlErrorDescription)
@@ skipping 43 matching lines @@
         m_client->didReceiveResponse(identifier, response, handle);
         return;
     }
 
     ASSERT(!m_fallbackRequestForServiceWorker);
 
     if (!m_sameOriginRequest && m_options.crossOriginRequestPolicy == UseAccessControl) {
         String accessControlErrorDescription;
         if (!passesAccessControlCheck(response, effectiveAllowCredentials(), securityOrigin(), accessControlErrorDescription)) {
             reportResponseReceived(identifier, response);
-            m_client->didFailAccessControlCheck(ResourceError(errorDomainBlinkInternal, 0, response.url().string(), accessControlErrorDescription));
+            m_client->didFailAccessControlCheck(ResourceError(errorDomainBlinkInternal, 0, response.url().string(), "Received response but it doesn't pass the access control check: " + accessControlErrorDescription));

[sof, 2015/06/25 11:24:18]

The prefixed text strikes me as redundant (and long) -- the error message makes
it implicitly clear that a response was received.

[tyoshino (SeeGerritForStatus), 2016/07/22 12:46:45]

OK. Removed

             return;
         }
     }
 
     m_client->didReceiveResponse(identifier, response, handle);
 }
 
 void DocumentThreadableLoader::setSerializedCachedMetadata(Resource*, const char* data, size_t size)
 {
     if (m_actualRequest)
@@ skipping 192 matching lines @@
         return DoNotAllowStoredCredentials;
     return m_resourceLoaderOptions.allowCredentials;
 }
 
 SecurityOrigin* DocumentThreadableLoader::securityOrigin() const
 {
     return m_securityOrigin ? m_securityOrigin.get() : m_document.securityOrigin();
 }
 
 } // namespace blink