WebView: Create UMA uploader

components/metrics/simple_metrics_log_uploader.h

+// Copyright 2017 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_SIMPLE_METRICS_LOG_UPLOADER_H_
+#define COMPONENTS_METRICS_SIMPLE_METRICS_LOG_UPLOADER_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "components/metrics/metrics_log_uploader.h"
+
+namespace metrics {
+
+// Intermediate abstraction layer to save simpler uploaders from dealing with
+// compression or hashes.

[Alexei Svitkine (slow), 2017/03/29 17:32:23]

Do we really need this? Seems all this is doing is adding a convenience
GzipUncompress() call - why not just do that in AwMetricsLogUploader directly?
You can still have the separate method split.

[paulmiller, 2017/03/29 17:39:32]

I did that initially, but checkdeps complained. Rather than add a dependency
from WebView onto third_party/zlib, I added SimpleMetricsLogUploader. Loose
coupling, and all that.

[Alexei Svitkine (slow), 2017/03/29 17:41:57]

Given this code is not being used by anything else, I think it should still live
in webview. You can just add zlib to the DEPS whitelist for webview.

[paulmiller, 2017/03/29 18:33:28]

Will do. I could go either way. On one hand, there's the fluffy extra
abstraction of SimpleMetricsLogUploader; on the other is making WebView aware of
gzip, which is arguably an implementation detail of the metrics code.

+class SimpleMetricsLogUploader : public MetricsLogUploader {
+ public:
+  virtual ~SimpleMetricsLogUploader() {}
+
+  void UploadLog(const std::string& compressed_log_data,
+                 const std::string& log_hash) override;
+
+  virtual void UploadLog(const std::string& uncompressed_log_data) = 0;
+};
+
+}  // namespace metrics
+
+#endif  // COMPONENTS_METRICS_SIMPLE_METRICS_LOG_UPLOADER_H_