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

chrome/browser/search/thumbnail_source.cc

Index: chrome/browser/search/thumbnail_source.cc
diff --git a/chrome/browser/search/thumbnail_source.cc b/chrome/browser/search/thumbnail_source.cc
index 26afe8922eabb198f196c6bf40fd4fe230f8c09d..cbfbb87e37823b2b8e4b093350996a9d74a6b6f0 100644
--- a/chrome/browser/search/thumbnail_source.cc
+++ b/chrome/browser/search/thumbnail_source.cc
@@ -88,6 +88,10 @@ ThumbnailSource::TaskRunnerForRequestPath(const std::string& path) const {
              : content::URLDataSource::TaskRunnerForRequestPath(path);
 }
 
+bool ThumbnailSource::AllowCaching() const {
+  return false;
+}
+
 bool ThumbnailSource::ShouldServiceRequest(
     const net::URLRequest* request) const {
   if (request->url().SchemeIs(chrome::kChromeSearchScheme))