Fix device_event_log component build, make NonThreadSafe (Take 2)

components/device_event_log/device_event_log_impl.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 COMPONENTS_DEVICE_EVENT_LOG_DEVICE_EVENT_LOG_IMPL_H_
 #define COMPONENTS_DEVICE_EVENT_LOG_DEVICE_EVENT_LOG_IMPL_H_
 
 #include <list>
 #include <string>
 
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
 #include "base/time/time.h"
 #include "components/device_event_log/device_event_log.h"
 
 namespace device_event_log {
 
-class DeviceEventLogImpl {
+// Implementation class for DEVICE_LOG.
+class DEVICE_EVENT_LOG_EXPORT DeviceEventLogImpl {
  public:
   struct LogEntry {
     LogEntry(const char* filedesc,
              int file_line,
              LogType log_type,
              LogLevel log_level,
              const std::string& event);
 
     std::string file;
     int file_line;
     LogType log_type;
     LogLevel log_level;
     std::string event;
     base::Time time;
     int count;
   };
 
-  explicit DeviceEventLogImpl(size_t max_entries);
+  explicit DeviceEventLogImpl(
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+      size_t max_entries);
   ~DeviceEventLogImpl();
 
   // Implements device_event_log::AddEntry.
   void AddEntry(const char* file,
                 int file_line,
                 LogType type,
                 LogLevel level,
                 const std::string& event);
 
   // Implements device_event_log::GetAsString.
@@ skipping 10 matching lines @@
                                    LogType type,
                                    LogLevel log_level,
                                    const std::string& event);
 
  private:
   friend class DeviceEventLogTest;
 
   typedef std::list<LogEntry> LogEntryList;
 
   void AddLogEntry(const LogEntry& entry);
+  void RemoveEntry();
 
   // For testing
   size_t max_entries() const { return max_entries_; }
   void set_max_entries_for_test(size_t entries) { max_entries_ = entries; }
 
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   size_t max_entries_;
   LogEntryList entries_;
+  base::WeakPtrFactory<DeviceEventLogImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DeviceEventLogImpl);
 };
 
 }  // namespace device_event_log
 
 #endif  // COMPONENTS_DEVICE_EVENT_LOG_DEVICE_EVENT_LOG_IMPL_H_