Cache feedback reports to disk in case of send failure.

chrome/browser/feedback/feedback_report.h

+// 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 CHROME_BROWSER_FEEDBACK_FEEDBACK_REPORT_H_
+#define CHROME_BROWSER_FEEDBACK_FEEDBACK_REPORT_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/files/file_path.h"
+#include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
+#include "base/time/time.h"
+
+namespace content {
+class BrowserContext;
+}
+
+namespace feedback {
+
+typedef base::Callback<void(const std::string&)> QueueCallback;
+
+// This class holds a feedback report. Once a report is created, a disk backup
+// for it is created automatically. This backup is deleted once this object

[Lei Zhang, 2014/02/01 01:37:22]

The statement about the backup being deleted doesn't hold. What happens if a
FeedbackReport gets deleted without anyone calling DeleteReportOnDisk() ?

[rkc, 2014/02/03 22:13:11]

Fixed.
Done.

+// dies.
+class FeedbackReport : public base::RefCountedThreadSafe<FeedbackReport> {

[Lei Zhang, 2014/02/01 01:37:22]

This class doesn't need to be RefCountedThreadSafe. Since both
WriteReportOnBlockingPool() and  DeleteReportOnBlockingPool() are essentially
fire and forget, you can just move them into an anonymous namespace and not be
part of FeedbackReport.

[rkc, 2014/02/03 22:13:11]

I use its ref-counted behavior to not have to manage it's lifetime while the
report is being moved around on the reports queue; not particularly for the
PostTask methods.

[Lei Zhang, 2014/02/03 22:26:51]

Is there any reason you need to use refcounting to keep track of
FeedbackReports? Why not just store a vector of  FeedbackReport* in
FeedbackUploader?

[rkc, 2014/02/03 22:41:26]

As discussed offline, changing to RefCounted versus RCTS.

+ public:
+  FeedbackReport(content::BrowserContext* context,
+                 const base::Time& upload_at,
+                 const std::string& data);
+
+  // Stops the disk write of the report and deletes the report file if already
+  // written.
+  void DeleteReportOnDisk();
+
+  base::Time upload_at() { return upload_at_; }

[Lei Zhang, 2014/02/01 01:37:22]

make the method const, return a const-ref

[rkc, 2014/02/03 22:13:11]

Done.

+  const std::string& data() { return data_; }

[Lei Zhang, 2014/02/01 01:37:22]

make the method const

[rkc, 2014/02/03 22:13:11]

Done.

+
+  // Loads the reports still on disk and queues then using the given callback.
+  // This call blocks on the file reads.
+  static void LoadReportsAndQueue(content::BrowserContext* context,
+                                  QueueCallback callback);
+
+ private:
+  friend class base::RefCountedThreadSafe<FeedbackReport>;
+  virtual ~FeedbackReport();
+
+  void WriteReportOnBlockingPool();
+  void DeleteReportOnBlockingPool();
+
+  // Name of the file corresponding to this report.
+  base::FilePath file_;
+
+  base::FilePath reports_path_;
+  base::Time upload_at_;  // Upload this report at or after this time.
+  std::string data_;
+
+  base::Lock file_access_lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(FeedbackReport);
+};
+
+}  // namespace feedback
+
+#endif  // CHROME_BROWSER_FEEDBACK_FEEDBACK_REPORT_H_