Log MediaSource parsing errors to the MediaLog so they can appear in chrome:media-internals.

media/base/media_log.h

 // Copyright (c) 2012 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 MEDIA_BASE_MEDIA_LOG_H_
 #define MEDIA_BASE_MEDIA_LOG_H_
 
+#include <sstream>
+#include <string>
+
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "media/base/media_export.h"
 #include "media/base/media_log_event.h"
 #include "media/base/pipeline.h"
 #include "media/base/pipeline_status.h"
 
 namespace media {
 
+// Indicates a string should be added to the log.
+// First parameter - The string to add to the log.
+typedef base::Callback<void(const std::string&)> LogCB;
+
+// Helper class to make it easier to use log_cb like DVLOG().
+class LogHelper {
+ public:
+  LogHelper(const LogCB& Log_cb);
+  ~LogHelper();
+
+  std::ostream& stream() { return stream_; }
+
+ private:
+  LogCB log_cb_;
+  std::stringstream stream_;
+};
+
+#define MEDIA_LOG(log_cb) LogHelper(log_cb).stream()
+
 class MEDIA_EXPORT MediaLog : public base::RefCountedThreadSafe<MediaLog> {
  public:
   // Convert various enums to strings.
   static const char* EventTypeToString(MediaLogEvent::Type type);
   static const char* PipelineStatusToString(PipelineStatus);
 
   MediaLog();
 
   // Add an event to this log. Overriden by inheritors to actually do something
   // with it.
   virtual void AddEvent(scoped_ptr<MediaLogEvent> event);
 
   // Helper methods to create events and their parameters.
   scoped_ptr<MediaLogEvent> CreateEvent(MediaLogEvent::Type type);
   scoped_ptr<MediaLogEvent> CreateBooleanEvent(
       MediaLogEvent::Type type, const char* property, bool value);
   scoped_ptr<MediaLogEvent> CreateStringEvent(
       MediaLogEvent::Type type, const char* property, const std::string& value);
   scoped_ptr<MediaLogEvent> CreateTimeEvent(
       MediaLogEvent::Type type, const char* property, base::TimeDelta value);
   scoped_ptr<MediaLogEvent> CreateLoadEvent(const std::string& url);
   scoped_ptr<MediaLogEvent> CreateSeekEvent(float seconds);
   scoped_ptr<MediaLogEvent> CreatePipelineStateChangedEvent(
       Pipeline::State state);
   scoped_ptr<MediaLogEvent> CreatePipelineErrorEvent(PipelineStatus error);
   scoped_ptr<MediaLogEvent> CreateVideoSizeSetEvent(
       size_t width, size_t height);
   scoped_ptr<MediaLogEvent> CreateBufferedExtentsChangedEvent(
       size_t start, size_t current, size_t end);
+  scoped_ptr<MediaLogEvent> CreateMediaSourceErrorEvent(
+      const std::string& error);
 
  protected:
   friend class base::RefCountedThreadSafe<MediaLog>;
   virtual ~MediaLog();
 
  private:
   // A unique (to this process) id for this MediaLog.
   int32 id_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaLog);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_MEDIA_LOG_H_