Not for submission. Keeping media log events

content/browser/media/media_internals.cc

Index: content/browser/media/media_internals.cc
diff --git a/content/browser/media/media_internals.cc b/content/browser/media/media_internals.cc
index f0b071a4e12fb3dda001b9506df53f42b98dec13..af0d3ab659d7f069a0694b9644ac251b409e694d 100644
--- a/content/browser/media/media_internals.cc
+++ b/content/browser/media/media_internals.cc
@@ -264,8 +264,11 @@ class MediaInternals::MediaInternalsUMAHandler : public NotificationObserver {
 
   // Helper function to save the event payload to RendererPlayerMap.
   void SavePlayerState(const media::MediaLogEvent& event,
+                       const base::string16& event_serialized,
                        int render_process_id);
 
+  std::vector<base::string16> GetHistoricalEvents();
+
  private:
   struct PipelineInfo {
     media::PipelineStatus last_pipeline_status;
@@ -276,6 +279,9 @@ class MediaInternals::MediaInternalsUMAHandler : public NotificationObserver {
     std::string audio_codec_name;
     std::string video_codec_name;
     std::string video_decoder;
+    // Remember media log events so that when a new media internals page is
+    // opened they can be replayed.
+    std::vector<base::string16> media_log_event_history;
     PipelineInfo()
         : last_pipeline_status(media::PIPELINE_OK),
           has_audio(false),
@@ -321,7 +327,7 @@ void MediaInternals::MediaInternalsUMAHandler::Observe(
   // by both SavePlayerState & LogAndClearPlayersInRenderer from different
   // threads.
   // Using base::Unretained() on MediaInternalsUMAHandler is safe since
-  // it is owned by MediaInternals and share the same lifetime
+  // it is owned by MediaInternals and shares the same lifetime.
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&MediaInternalsUMAHandler::LogAndClearPlayersInRenderer,
@@ -330,9 +336,12 @@ void MediaInternals::MediaInternalsUMAHandler::Observe(
 
 void MediaInternals::MediaInternalsUMAHandler::SavePlayerState(
     const media::MediaLogEvent& event,
+    const base::string16& event_serialized,
     int render_process_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   PlayerInfoMap& player_info = renderer_info_[render_process_id];
+  // This can grow unbounded..
+  player_info[event.id].media_log_event_history.push_back(event_serialized);
   switch (event.type) {
     case media::MediaLogEvent::PIPELINE_ERROR: {
       int status;
@@ -450,6 +459,23 @@ void MediaInternals::MediaInternalsUMAHandler::LogAndClearPlayersInRenderer(
     ReportUMAForPipelineStatus(it->second);
     players_it->second.erase(it++);
   }
+  renderer_info_.erase(players_it);
+}
+
+std::vector<base::string16>
+MediaInternals::MediaInternalsUMAHandler::GetHistoricalEvents() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  std::vector<base::string16> all_events;
+  for (const auto& renderer_info_it : renderer_info_) {
+    for (const auto& player_info_it : renderer_info_it.second) {
+      const auto& player_events = player_info_it.second.media_log_event_history;
+      all_events.insert(all_events.end(), player_events.begin(),
+                        player_events.end());
+    }
+  }
+
+  return all_events;
 }
 
 MediaInternals* MediaInternals::GetInstance() {
@@ -493,8 +519,9 @@ void MediaInternals::OnMediaEvents(
       dict.Set("params", event->params.DeepCopy());
     }
 
-    SendUpdate(SerializeUpdate("media.onMediaEvent", &dict));
-    uma_handler_->SavePlayerState(*event, render_process_id);
+    const base::string16 update(SerializeUpdate("media.onMediaEvent", &dict));
+    SendUpdate(update);
+    uma_handler_->SavePlayerState(*event, update, render_process_id);
   }
 }
 
@@ -514,6 +541,12 @@ void MediaInternals::RemoveUpdateCallback(const UpdateCallback& callback) {
   NOTREACHED();
 }
 
+void MediaInternals::SendHistoricalMediaEvents() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  for (const auto& event : uma_handler_->GetHistoricalEvents())
+    SendUpdate(event);
+}
+
 void MediaInternals::SendAudioStreamData() {
   base::string16 audio_stream_update;
   {