Fix device_event_log component build, make NonThreadSafe (Take 2)

components/device_event_log/device_event_log_impl.h

Index: components/device_event_log/device_event_log_impl.h
diff --git a/components/device_event_log/device_event_log_impl.h b/components/device_event_log/device_event_log_impl.h
index ee33d653337a12dbcd17e04fa0835278f89de060..6c3dffeb726f8ce076424e3f5cd065a467c294d1 100644
--- a/components/device_event_log/device_event_log_impl.h
+++ b/components/device_event_log/device_event_log_impl.h
@@ -8,12 +8,16 @@
 #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,
@@ -31,7 +35,9 @@ class DeviceEventLogImpl {
     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.
@@ -62,13 +68,16 @@ class DeviceEventLogImpl {
   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);
 };