Move MimeTypeResourceHandler before ThrottlingResourceHandler

chrome/browser/renderer_host/safe_browsing_resource_throttle.cc

 // Copyright (c) 2012 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/renderer_host/safe_browsing_resource_throttle.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 151 matching lines @@
   if (state_ == STATE_CHECKING_URL ||
       state_ == STATE_DISPLAYING_BLOCKING_PAGE) {
     defer_state_ = DEFERRED_PROCESSING;
     defer_start_time_ = base::TimeTicks::Now();
     *defer = true;
     BeginNetLogEvent(NetLog::TYPE_SAFE_BROWSING_DEFERRED, request_->url(),
                      "defer_reason", "at_response");
   }
 }
 
+bool SafeBrowsingResourceThrottle::MustProcessResponseBeforeReadingBody() {
+  // On Android, SafeBrowsing may only decide to cancel the request when the
+  // response has been received. Therefore, no part of it should be cached
+  // until this ResourceThrottle has been able to check the response. This
+  // prevents the following scenario:
+  //   1) A request is made for foo.com which has been hacked.
+  //   2) The request is only canceled at WillProcessResponse stage, but part of
+  //   it has been cached.
+  //   3) foo.com is no longer hacked and removed from the SafeBrowsing list.
+  //   4) The user requests foo.com, which is not on the SafeBrowsing list. This
+  //   is deemed safe. However, the resource is actually served from cache,
+  //   using the version that was previously stored.
+  //   5) This results in the  user accessing an unsafe resource without being
+  //   notified that it's dangerous.
+  // TODO(clamy): Add a browser test that checks this specific scenario.
+  return true;
+}
+
 void SafeBrowsingResourceThrottle::WillRedirectRequest(
     const net::RedirectInfo& redirect_info,
     bool* defer) {
   CHECK_EQ(defer_state_, DEFERRED_NONE);
 
   // Prev check completed and was safe.
   if (state_ == STATE_NONE) {
     // Save the redirect urls for possible malware detail reporting later.
     redirect_urls_.push_back(redirect_info.new_url);
 
@@ skipping 206 matching lines @@
                        unchecked_redirect_url_, "defer_reason",
                        "resumed_redirect");
     }
   }
 
   if (resume) {
     defer_state_ = DEFERRED_NONE;
     controller()->Resume();
   }
 }