Move MimeTypeResourceHandler before ThrottlingResourceHandler

content/browser/loader/resource_dispatcher_host_impl.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.
 
 // See http://dev.chromium.org/developers/design-documents/multi-process-resource-loading
 
 #include "content/browser/loader/resource_dispatcher_host_impl.h"
 
 #include <stddef.h>
 
@@ skipping 31 matching lines @@
 #include "content/browser/download/download_resource_handler.h"
 #include "content/browser/download/save_file_manager.h"
 #include "content/browser/download/save_file_resource_handler.h"
 #include "content/browser/frame_host/frame_tree.h"
 #include "content/browser/frame_host/navigation_request_info.h"
 #include "content/browser/frame_host/navigator.h"
 #include "content/browser/loader/async_resource_handler.h"
 #include "content/browser/loader/async_revalidation_manager.h"
 #include "content/browser/loader/cross_site_resource_handler.h"
 #include "content/browser/loader/detachable_resource_handler.h"
+#include "content/browser/loader/intercepting_resource_handler.h"
 #include "content/browser/loader/loader_delegate.h"
-#include "content/browser/loader/mime_type_resource_handler.h"
+#include "content/browser/loader/mime_sniffing_resource_handler.h"
 #include "content/browser/loader/navigation_resource_handler.h"
 #include "content/browser/loader/navigation_resource_throttle.h"
 #include "content/browser/loader/navigation_url_loader_impl_core.h"
 #include "content/browser/loader/power_save_block_resource_throttle.h"
 #include "content/browser/loader/redirect_to_file_resource_handler.h"
 #include "content/browser/loader/resource_message_filter.h"
 #include "content/browser/loader/resource_request_info_impl.h"
 #include "content/browser/loader/stream_resource_handler.h"
 #include "content/browser/loader/sync_resource_handler.h"
 #include "content/browser/loader/throttling_resource_handler.h"
@@ skipping 1585 matching lines @@
     std::unique_ptr<ResourceHandler> handler) {
   // PlzNavigate: do not add ResourceThrottles for main resource requests from
   // the renderer.  Decisions about the navigation should have been done in the
   // initial request.
   if (IsBrowserSideNavigationEnabled() && IsResourceTypeFrame(resource_type) &&
       child_id != -1) {
     DCHECK(request->url().SchemeIs(url::kBlobScheme));
     return handler;
   }
 
-  PluginService* plugin_service = nullptr;
-#if defined(ENABLE_PLUGINS)
-  plugin_service = PluginService::GetInstance();
-#endif
-  // Insert a buffered event handler before the actual one.
-  handler.reset(new MimeTypeResourceHandler(std::move(handler), this,
-                                            plugin_service, request));
+  // The InterceptingResourceHandler will replace its next handler with an
+  // appropriate one based on the MIME type of the response if needed. It
+  // should be placed at the end of the chain, just before |handler|.
+  handler.reset(new InterceptingResourceHandler(std::move(handler), request));
+  InterceptingResourceHandler* intercepting_handler =
+      static_cast<InterceptingResourceHandler*>(handler.get());
 
   ScopedVector<ResourceThrottle> throttles;
 
   // Add a NavigationResourceThrottle for navigations.
   // PlzNavigate: the throttle is unnecessary as communication with the UI
   // thread is handled by the NavigationURLloader.
   if (!IsBrowserSideNavigationEnabled() && IsResourceTypeFrame(resource_type))
     throttles.push_back(new NavigationResourceThrottle(request, delegate()));
 
   if (delegate_) {
@@ skipping 10 matching lines @@
         request->url().host(),
         BrowserThread::GetTaskRunnerForThread(BrowserThread::UI),
         BrowserThread::GetTaskRunnerForThread(BrowserThread::FILE)));
   }
 
   // TODO(ricea): Stop looking this up so much.
   ResourceRequestInfoImpl* info = ResourceRequestInfoImpl::ForRequest(request);
   throttles.push_back(scheduler_->ScheduleRequest(child_id, route_id,
                                                   info->IsAsync(), request));
 
-  handler.reset(new ThrottlingResourceHandler(std::move(handler), request,
-                                              std::move(throttles)));
+  // Split the handler in two groups: the ones that need to execute
+  // WillProcessResponse before mime sniffing and the others.
+  // TODO(clamy): ScopedVector is deprecated. The interface should be changed
+  // to use vectors instead.
+  ScopedVector<ResourceThrottle> pre_mime_sniffing_throttles;
+  ScopedVector<ResourceThrottle> post_mime_sniffing_throttles;
+  for (auto throttle : throttles) {
+    if (throttle->MustProcessResponseBeforeMimeSniffing())
+      pre_mime_sniffing_throttles.push_back(throttle);
+    else
+      post_mime_sniffing_throttles.push_back(throttle);

[mmenke, 2016/07/27 19:34:01]

nit:  Use braces with else-if.

[clamy, 2016/08/17 12:47:35]

Done.

+  }
+  throttles.weak_clear();
+
+  // Add the post mime sniffing throttles.
+  handler.reset(new ThrottlingResourceHandler(
+      std::move(handler), request, std::move(post_mime_sniffing_throttles)));
+
+  PluginService* plugin_service = nullptr;
+#if defined(ENABLE_PLUGINS)
+  plugin_service = PluginService::GetInstance();
+#endif
+
+  // Insert a buffered event handler to sniff the mime type.
+  // Note: all ResourceHandler following the MimeSniffingResourceHandler should
+  // expect OnWillRead to be called *before* OnResponseStarted as part of the
+  // mime sniffing process.
+  handler.reset(new MimeSniffingResourceHandler(
+      std::move(handler), this, plugin_service, intercepting_handler, request));
+
+  // Add the pre mime sniffing throttles.
+  handler.reset(new ThrottlingResourceHandler(
+      std::move(handler), request, std::move(pre_mime_sniffing_throttles)));
 
   return handler;
 }
 
 void ResourceDispatcherHostImpl::OnReleaseDownloadedFile(int request_id) {
   UnregisterDownloadedTempFile(filter_->child_id(), request_id);
 }
 
 void ResourceDispatcherHostImpl::OnDidChangePriority(
     int request_id,
@@ skipping 888 matching lines @@
   ssl.cert_id = GetCertStore()->StoreCert(ssl_info.cert.get(), child_id);
   response->head.security_info = SerializeSecurityInfo(ssl);
 }
 
 CertStore* ResourceDispatcherHostImpl::GetCertStore() {
   return cert_store_for_testing_ ? cert_store_for_testing_
                                  : CertStore::GetInstance();
 }
 
 }  // namespace content