Add log source to read from one DebugDaemon log

chrome/browser/chromeos/system_logs/single_debug_daemon_log_source.cc

+// 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.
+
+#include "chrome/browser/chromeos/system_logs/single_debug_daemon_log_source.h"
+
+#include "base/bind.h"
+#include "chromeos/dbus/dbus_thread_manager.h"
+#include "chromeos/dbus/debug_daemon_client.h"
+#include "components/feedback/anonymizer_tool.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace system_logs {
+
+namespace {
+
+using SupportedSource = SingleDebugDaemonLogSource::SupportedSource;
+
+// Converts a logs source type to the corresponding file path, relative to the
+// base system log directory path. In the future, if non-file source types are
+// added, this function should return an empty file path.

[afakhry, 2017/06/22 22:20:58]

Copy-and-paste comment. Please modify! :)

[Simon Que, 2017/06/22 22:38:27]

Done.

+std::string GetLogName(SupportedSource source_type) {
+  switch (source_type) {
+    case SupportedSource::kModetest:
+      return "modetest";
+    case SupportedSource::kLsusb:
+      return "lsusb";
+  }
+  NOTREACHED();
+  return "";
+}
+
+}  // namespace
+
+SingleDebugDaemonLogSource::SingleDebugDaemonLogSource(
+    SupportedSource source_type)
+    : SystemLogsSource(GetLogName(source_type)), weak_ptr_factory_(this) {}
+
+SingleDebugDaemonLogSource::~SingleDebugDaemonLogSource() {}
+
+void SingleDebugDaemonLogSource::Fetch(const SysLogsSourceCallback& callback) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  DCHECK(!callback.is_null());
+
+  chromeos::DebugDaemonClient* client =
+      chromeos::DBusThreadManager::Get()->GetDebugDaemonClient();
+
+  client->GetLog(source_name(),

[afakhry, 2017/06/22 22:20:59]

I don't see this function belonging to DebugDaemonClient at all! Was that added
recently?

https://cs.chromium.org/chromium/src/chromeos/dbus/debug_daemon_client.h?q=De...

[Simon Que, 2017/06/22 22:38:27]

That function is being added in a CL that this one depends on:
https://codereview.chromium.org/2944403002#ps20001

+                 base::Bind(&SingleDebugDaemonLogSource::OnFetchComplete,
+                            weak_ptr_factory_.GetWeakPtr(), callback));
+}
+
+void SingleDebugDaemonLogSource::OnFetchComplete(
+    const SysLogsSourceCallback& callback,
+    bool success,

[afakhry, 2017/06/22 22:20:59]

Can you check "success" and add a test for that?

[Simon Que, 2017/06/22 22:38:27]

I can return an empty result on !success, but I don't know how to test for it in
the unit test.

One idea I had was to update FakeDebugDaemonClient::GetLog() to return !success
if log_name="invalid", but SingleDebugDaemonLogSource's constructor only takes
valid enums as an arg.

[afakhry, 2017/06/22 23:34:15]

Forget about this test request. It's not worth it.

+    const std::map<std::string, std::string>& result) const {
+  // |result| and |response| are the same type, but |result| is passed in from
+  // DebugDaemonClient, which does not use the SystemLogsResponse alias.
+  SystemLogsResponse response;
+  feedback::AnonymizerTool anonymizer;
+  for (auto& entry : result)
+    response[entry.first] = anonymizer.Anonymize(entry.second);

[afakhry, 2017/06/22 22:20:58]

Nit: emplace(key, val);

[Simon Que, 2017/06/22 22:38:27]

Done.

+
+  callback.Run(&response);
+}
+
+}  // namespace system_logs