[Offline Prefetech] Send GetOperationReqest to the server

components/offline_pages/core/prefetch/prefetch_request_fetcher.cc

Index: components/offline_pages/core/prefetch/prefetch_request_fetcher.cc
diff --git a/components/offline_pages/core/prefetch/prefetch_request_fetcher.cc b/components/offline_pages/core/prefetch/prefetch_request_fetcher.cc
index 039faf1d36cbaeb7c435cd13448a9bd3255f80fc..b2cb2a88ed7223e713ff0facd4f7d41f29e14639 100644
--- a/components/offline_pages/core/prefetch/prefetch_request_fetcher.cc
+++ b/components/offline_pages/core/prefetch/prefetch_request_fetcher.cc
@@ -6,6 +6,7 @@
 
 #include "base/logging.h"
 #include "net/base/load_flags.h"
+#include "net/http/http_request_headers.h"
 #include "net/http/http_status_code.h"
 #include "net/traffic_annotation/network_traffic_annotation.h"
 #include "net/url_request/url_fetcher.h"
@@ -16,11 +17,18 @@
 namespace offline_pages {
 
 namespace {
+
+const char kPrefetchSever[] =
+    "http://staging-offlinepages-pa.sandbox.googleapis.com/";
+
+// Content type needed in order to communicate with the server in binary
+// proto format.
 const char kRequestContentType[] = "application/x-protobuf";
+
 }  // namespace
 
 PrefetchRequestFetcher::PrefetchRequestFetcher(
-    const GURL& url,
+    const std::string& url_path,
     const std::string& message,
     net::URLRequestContextGetter* request_context_getter,
     const FinishedCallback& callback)
@@ -46,12 +54,21 @@ PrefetchRequestFetcher::PrefetchRequestFetcher(
           policy_exception_justification:
             "Not implemented, considered not useful."
         })");
-  url_fetcher_ = net::URLFetcher::Create(url, net::URLFetcher::POST, this,
-                                         traffic_annotation);
+  url_fetcher_ = net::URLFetcher::Create(
+      GURL(kPrefetchSever + url_path),

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

This feels like it should be more like

GURL::Replacements replacements;
replacements.SetPathString(url_path);

GURL fetch_url = GURL(kPrefetchServer).ReplaceComponents(replacements);
url_fetcher_ = net::URLFetcher::Create(fetch_url, ...);

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

Since both server and path are hard coded constant strings, concatenating them
seems to be good enough. I like your proposal, but it seems to a bit too
complicated for our simple case.

[dewittj, 2017/05/16 23:06:22]

URL path is not hard coded in the GET case, correct?  Replacements encodes
components correctly, in case the operation name needs it.  Also, in the future
if we need to alter the URL string it won't be a risk, just the path will be
changed.

[jianli, 2017/05/16 23:52:33]

Make sense. Done.

+      message.empty() ? net::URLFetcher::GET : net::URLFetcher::POST, this,
+      traffic_annotation);
   url_fetcher_->SetRequestContext(request_context_getter_.get());
   url_fetcher_->SetAutomaticallyRetryOn5xx(false);
   url_fetcher_->SetAutomaticallyRetryOnNetworkChanges(0);
-  url_fetcher_->SetUploadData(kRequestContentType, message);
+  if (message.empty()) {
+    std::string extra_header(net::HttpRequestHeaders::kContentType);
+    extra_header += ": ";
+    extra_header += kRequestContentType;
+    url_fetcher_->AddExtraRequestHeader(extra_header);
+  } else {
+    url_fetcher_->SetUploadData(kRequestContentType, message);
+  }
   url_fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
                              net::LOAD_DO_NOT_SAVE_COOKIES);
   url_fetcher_->Start();