Faster Reload: Specify AllowCaching = false for some URLDataSources that need it

chrome/browser/search/thumbnail_source.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/search/thumbnail_source.h"
 
 #include <stddef.h>
 
 #include "base/callback.h"
 #include "base/memory/ptr_util.h"
@@ skipping 70 matching lines @@
 
 scoped_refptr<base::SingleThreadTaskRunner>
 ThumbnailSource::TaskRunnerForRequestPath(const std::string& path) const {
   // TopSites can be accessed from the IO thread. Otherwise, the URLs should be
   // accessed on the UI thread.
   return thumbnail_service_.get()
              ? nullptr
              : content::URLDataSource::TaskRunnerForRequestPath(path);
 }
 
+bool ThumbnailSource::AllowCaching() const {
+  return false;
+}
+
 bool ThumbnailSource::ShouldServiceRequest(
     const net::URLRequest* request) const {
   if (request->url().SchemeIs(chrome::kChromeSearchScheme))
     return InstantIOContext::ShouldServiceRequest(request);
   return URLDataSource::ShouldServiceRequest(request);
 }
 
 void ThumbnailSource::ExtractPageAndThumbnailUrls(
     const std::string& path,
     GURL* page_url,
@@ skipping 24 matching lines @@
   const SkBitmap* bitmap = image.ToSkBitmap();
   scoped_refptr<base::RefCountedBytes> encoded_data(
       new base::RefCountedBytes());
   if (!suggestions::EncodeSkBitmapToJPEG(*bitmap, &encoded_data->data())) {
     callback.Run(default_thumbnail_.get());
     return;
   }
 
   callback.Run(encoded_data.get());
 }