Make MetricsService upload logs through an interface.

components/metrics/metrics_log_uploader.h

Index: components/metrics/metrics_log_uploader.h
===================================================================
--- components/metrics/metrics_log_uploader.h	(revision 0)
+++ components/metrics/metrics_log_uploader.h	(revision 0)
@@ -0,0 +1,44 @@
+// 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_METRICS_LOG_UPLOADER_H_
+#define COMPONENTS_METRICS_METRICS_LOG_UPLOADER_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/macros.h"
+
+namespace metrics {
+
+// MetricsLogUploader is an abstract base class for uploading UMA logs on behalf
+// of MetricsService.
+class MetricsLogUploader {
+ public:
+  // Constructs the uploader that will upload logs to the specified |server_url|
+  // with the given |mime_type|. The |on_upload_complete| callback will be
+  // called with the HTTP response code of the upload or with -1 on an error.
+  MetricsLogUploader(const std::string& server_url,
+                     const std::string& mime_type,
+                     const base::Callback<void(int)>& on_upload_complete);
+  virtual ~MetricsLogUploader();
+
+  // Uploads a log with the specified |log_data| and |log_hash|. |log_hash| is
+  // expected to be the hex-encoded SHA1 hash of |log_data|.
+  virtual bool UploadLog(const std::string& log_data,
+                         const std::string& log_hash) = 0;
+
+ protected:
+  const std::string server_url_;
+  const std::string mime_type_;
+  const base::Callback<void(int)> on_upload_complete_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MetricsLogUploader);
+};
+
+}  // namespace metrics
+
+#endif  // COMPONENTS_METRICS_METRICS_LOG_UPLOADER_H_