Fixes a DCHECK when visiting chrome://theme....

chrome/browser/renderer_host/resource_dispatcher_host.cc

 // Copyright (c) 2010 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 "chrome/browser/renderer_host/resource_dispatcher_host.h"
 
 #include <vector>
 
@@ skipping 1280 matching lines @@
 
   info->set_has_started_reading(true);
   return request->Read(buf, buf_size, bytes_read);
 }
 
 void ResourceDispatcherHost::OnReadCompleted(URLRequest* request,
                                              int bytes_read) {
   DCHECK(request);
   RESOURCE_LOG("OnReadCompleted: " << request->url().spec());
   ResourceDispatcherHostRequestInfo* info = InfoForRequest(request);
+
+  // OnReadCompleted can be called without Read (e.g., for chrome:// URLs).
+  // Make sure we know that a read has begun.
+  info->set_has_started_reading(true);
+
   if (PauseRequestIfNeeded(info)) {
     info->set_paused_read_bytes(bytes_read);
     RESOURCE_LOG("OnReadCompleted pausing: " << request->url().spec());
     return;
   }
 
   if (request->status().is_success() && CompleteRead(request, &bytes_read)) {
     // The request can be paused if we realize that the renderer is not
     // servicing messages fast enough.
     if (info->pause_count() == 0 &&
@@ skipping 503 matching lines @@
     // them.
     case ResourceType::IMAGE:
       return net::LOWEST;
 
     default:
       // When new resource types are added, their priority must be considered.
       NOTREACHED();
       return net::LOW;
   }
 }