Improve crashpad integration (issue #1995)

- Crash reporting is enabled and configured using a "crash_reporter.cfg"
  file. See comments in include/cef_crash_util.h and tools/crash_server.py
  for usage.

libcef/common/cef_crash_report_upload_thread.h

@@ -0,0 +1,42 @@
+// Copyright 2016 The Chromium Embedded Framework 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 CEF_LIBCEF_COMMON_CEF_CRASH_REPORT_UPLOAD_THREAD_H_
+#define CEF_LIBCEF_COMMON_CEF_CRASH_REPORT_UPLOAD_THREAD_H_
+
+#include "third_party/crashpad/crashpad/handler/crash_report_upload_thread.h"
+
+class CefCrashReportUploadThread : public crashpad::CrashReportUploadThread {
+ public:
+  CefCrashReportUploadThread(crashpad::CrashReportDatabase* database,
+                             const std::string& url,
+                             bool rate_limit,
+                             int max_uploads);
+  ~CefCrashReportUploadThread();
+
+ private:
+  void ProcessPendingReports() override;
+  void ProcessPendingReport(
+    const crashpad::CrashReportDatabase::Report& report) override;
+
+  bool UploadsEnabled() const;
+
+  bool MaxUploadsEnabled() const;
+  bool MaxUploadsExceeded() const;
+
+  bool BackoffPending() const;
+  void IncreaseBackoff();
+  void ResetBackoff();
+
+  int max_uploads_;
+
+  // Track the number of uploads that have completed within the last 24 hours.
+  // Only used when RateLimitEnabled() is true. Value is reset each time
+  // ProcessPendingReports() is called.
+  int recent_upload_ct_ = 0;
+
+  DISALLOW_COPY_AND_ASSIGN(CefCrashReportUploadThread);
+};
+
+#endif  // CEF_LIBCEF_COMMON_CEF_CRASH_REPORT_UPLOAD_THREAD_H_