[Sync] Add histograms for sync response/error codes

sync/internal_api/http_bridge.cc

 // Copyright 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 "sync/internal_api/public/http_bridge.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/metrics/sparse_histogram.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "net/base/load_flags.h"
 #include "net/base/net_errors.h"
 #include "net/http/http_cache.h"
 #include "net/http/http_network_layer.h"
 #include "net/http/http_request_headers.h"
 #include "net/http/http_response_headers.h"
 #include "net/url_request/static_http_user_agent_settings.h"
@@ skipping 405 matching lines @@
 
   fetch_state_.end_time = base::Time::Now();
   fetch_state_.request_completed = true;
   fetch_state_.request_succeeded =
       (net::URLRequestStatus::SUCCESS == source->GetStatus().status());
   fetch_state_.http_response_code = source->GetResponseCode();
   fetch_state_.error_code = source->GetStatus().error();
 
   if (fetch_state_.request_succeeded)
     LogTimeout(false);
+  UMA_HISTOGRAM_SPARSE_SLOWLY("Sync.URLFetchResponse",
+                              source->GetStatus().is_success()
+                                  ? source->GetResponseCode()
+                                  : source->GetStatus().ToNetError());
   UMA_HISTOGRAM_LONG_TIMES("Sync.URLFetchTime",
                            fetch_state_.end_time - fetch_state_.start_time);
 
   // Use a real (non-debug) log to facilitate troubleshooting in the wild.
   VLOG(2) << "HttpBridge::OnURLFetchComplete for: "
           << fetch_state_.url_poster->GetURL().spec();
   VLOG(1) << "HttpBridge received response code: "
           << fetch_state_.http_response_code;
 
   source->GetResponseAsString(&fetch_state_.response_content);
@@ skipping 88 matching lines @@
   int64 sane_time_ms = 0;
   if (base::StringToInt64(sane_time_str, &sane_time_ms)) {
     network_time_update_callback_.Run(
         base::Time::FromJsTime(sane_time_ms),
         base::TimeDelta::FromMilliseconds(1),
         fetch_state_.end_time - fetch_state_.start_time);
   }
 }
 
 }  // namespace syncer