Make MetricsService upload logs through an interface.

components/metrics/net/net_metrics_log_uploader.h

Index: components/metrics/net/net_metrics_log_uploader.h
===================================================================
--- components/metrics/net/net_metrics_log_uploader.h	(revision 0)
+++ components/metrics/net/net_metrics_log_uploader.h	(revision 0)
@@ -0,0 +1,54 @@
+// Copyright 2014 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.
+
+#ifndef COMPONENTS_METRICS_NET_NET_METRICS_LOG_UPLOADER_H_
+#define COMPONENTS_METRICS_NET_NET_METRICS_LOG_UPLOADER_H_
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "components/metrics/metrics_log_uploader.h"
+#include "net/url_request/url_fetcher_delegate.h"
+
+namespace net {
+class URLFetcher;
+class URLRequestContextGetter;
+}
+
+namespace metrics {
+
+// Implementation of MetricsLogUploader using the Chrome network stack.
+class NetMetricsLogUploader : public MetricsLogUploader,
+                              public net::URLFetcherDelegate {
+ public:
+  // Constructs a NetMetricsLogUploader with the specified request context and
+  // other params (see comments on MetricsLogUploader for details). The caller
+  // must ensure that |request_context_getter| remains valid for the lifetime
+  // of this class.
+  NetMetricsLogUploader(net::URLRequestContextGetter* request_context_getter,
+                        const std::string& server_url,
+                        const std::string& mime_type,
+                        const base::Callback<void(int)>& on_upload_complete);
+  virtual ~NetMetricsLogUploader();
+
+  // MetricsLogUploader:
+  virtual bool UploadLog(const std::string& log_data,
+                         const std::string& log_hash) OVERRIDE;
+
+ private:
+  // net::URLFetcherDelegate:
+  virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
+
+  // The request context for fetches done using the network stack.
+  net::URLRequestContextGetter* const request_context_getter_;
+
+  // The outstanding transmission appears as a URL Fetch operation.
+  scoped_ptr<net::URLFetcher> current_fetch_;
+
+  DISALLOW_COPY_AND_ASSIGN(NetMetricsLogUploader);
+};
+
+}  // namespace metrics
+
+#endif  // COMPONENTS_METRICS_NET_NET_METRICS_LOG_UPLOADER_H_