[Offline Prefetech] Send GetOperationReqest to the server

components/offline_pages/core/prefetch/prefetch_request_fetcher.h

Index: components/offline_pages/core/prefetch/prefetch_request_fetcher.h
diff --git a/components/offline_pages/core/prefetch/prefetch_request_fetcher.h b/components/offline_pages/core/prefetch/prefetch_request_fetcher.h
index 09c543ab0bbfd0352ad4bda17e6792013e2043f6..0134510f3c8fe6afd7b285e29fb2b6b1e1e9e24e 100644
--- a/components/offline_pages/core/prefetch/prefetch_request_fetcher.h
+++ b/components/offline_pages/core/prefetch/prefetch_request_fetcher.h
@@ -11,19 +11,21 @@
 #include "components/offline_pages/core/prefetch/prefetch_types.h"
 #include "net/url_request/url_fetcher_delegate.h"
 
-class GURL;
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace offline_pages {
 
+// Asynchronously fetches the offline prefetch related data from the server.
 class PrefetchRequestFetcher : public net::URLFetcherDelegate {
  public:
   using FinishedCallback = base::Callback<void(PrefetchRequestStatus status,
                                                const std::string& data)>;
 
-  PrefetchRequestFetcher(const GURL& url,
+  // If |message| is empty, the GET request is sent. Otherwise, the POST request
+  // is sent with |message| as post data.
+  PrefetchRequestFetcher(const std::string& url_path,

[dewittj, 2017/05/16 18:30:20]

Can you make two constructors, one that is for posting data, and one for get? 

[jianli, 2017/05/16 22:44:40]

Changed to 2 static creator methods since their names are even clearer than
different constructors.

                          const std::string& message,
                          net::URLRequestContextGetter* request_context_getter,
                          const FinishedCallback& callback);