Coverity: Pass values by reference.

chrome/browser/extensions/image_loading_tracker.cc

 // Copyright (c) 2011 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/extensions/image_loading_tracker.h"
 
 #include "base/file_util.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_resource.h"
 #include "content/browser/browser_thread.h"
@@ skipping 29 matching lines @@
   void LoadImage(const ExtensionResource& resource,
                  const gfx::Size& max_size,
                  int id) {
     DCHECK(!BrowserThread::CurrentlyOn(BrowserThread::FILE));
     BrowserThread::PostTask(
         BrowserThread::FILE, FROM_HERE,
         NewRunnableMethod(this, &ImageLoader::LoadOnFileThread, resource,
                           max_size, id));
   }
 
-  void LoadOnFileThread(ExtensionResource resource,
+  void LoadOnFileThread(const ExtensionResource& resource,
                         const gfx::Size& max_size,
                         int id) {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 
     // Read the file from disk.
     std::string file_contents;
     FilePath path = resource.GetFilePath();
     if (path.empty() || !file_util::ReadFileToString(path, &file_contents)) {
       ReportBack(NULL, resource, gfx::Size(), id);
       return;
@@ skipping 129 matching lines @@
   // Remove all entries in the load_map_ referencing the extension. This ensures
   // we don't attempt to cache the image when the load completes.
   for (LoadMap::iterator i = load_map_.begin(); i != load_map_.end();) {
     if (i->second == extension) {
       load_map_.erase(i++);
     } else {
       ++i;
     }
   }
 }