Add a command line flag for dumping trace events to VLOG

base/debug/trace_event_impl.cc

Index: base/debug/trace_event_impl.cc
diff --git a/base/debug/trace_event_impl.cc b/base/debug/trace_event_impl.cc
index 860d989489488b8407292b3ba9169926e39e7463..65626f1278c08bcb2695f24c6f0a129c8a2f762c 100644
--- a/base/debug/trace_event_impl.cc
+++ b/base/debug/trace_event_impl.cc
@@ -228,6 +228,33 @@ class TraceBufferVector : public TraceBuffer {
   DISALLOW_COPY_AND_ASSIGN(TraceBufferVector);
 };
 
+class TraceBufferDiscardsEvents : public TraceBuffer {
+ public:
+  virtual ~TraceBufferDiscardsEvents() { }
+
+  virtual void AddEvent(const TraceEvent& event) { }
+  virtual bool HasMoreEvents() const { return false; }
+
+  virtual const TraceEvent& NextEvent() {
+    NOTREACHED();
+    return *static_cast<TraceEvent*>(NULL);
+  }
+
+  virtual bool IsFull() const { return false; }
+
+  virtual size_t CountEnabledByName(const unsigned char* category,
+                                    const std::string& event_name) const {
+    return 0;
+  }
+
+  virtual size_t Size() const { return 0; }
+
+  virtual const TraceEvent& GetEventAt(size_t index) const {
+    NOTREACHED();
+    return *static_cast<TraceEvent*>(NULL);
+  }
+};
+
 ////////////////////////////////////////////////////////////////////////////////
 //
 // TraceEvent
@@ -922,6 +949,8 @@ void TraceLog::SetNotificationCallback(
 TraceBuffer* TraceLog::GetTraceBuffer() {
   if (trace_options_ & RECORD_CONTINUOUSLY)
     return new TraceBufferRingBuffer();
+  else if (trace_options_ & ECHO_TO_VLOG)
+    return new TraceBufferDiscardsEvents();
   return new TraceBufferVector();
 }
 
@@ -987,6 +1016,12 @@ void TraceLog::AddTraceEventWithThreadIdAndTimestamp(
     unsigned char flags) {
   DCHECK(name);
 
+  TimeDelta duration;
+  if (phase == TRACE_EVENT_PHASE_END && trace_options_ & ECHO_TO_VLOG) {
+    duration = timestamp - thread_event_start_times_[thread_id].top();
+    thread_event_start_times_[thread_id].pop();
+  }
+
   if (flags & TRACE_EVENT_FLAG_MANGLE_ID)
     id ^= process_id_hash_;
 
@@ -1037,6 +1072,32 @@ void TraceLog::AddTraceEventWithThreadIdAndTimestamp(
       }
     }
 
+    if (trace_options_ & ECHO_TO_VLOG) {
+      std::string thread_name = thread_names_[thread_id];
+      if (thread_colors_.find(thread_name) == thread_colors_.end())
+        thread_colors_[thread_name] = (thread_colors_.size() % 6) + 1;
+
+      std::ostringstream log;
+      log << base::StringPrintf("%s: \e[0;3%dm",
+                                thread_name.c_str(),
+                                thread_colors_[thread_name]);
+
+      size_t depth = 0;
+      if (thread_event_start_times_.find(thread_id) !=
+          thread_event_start_times_.end())
+        depth = thread_event_start_times_[thread_id].size();
+
+      for (size_t i = 0; i < depth; ++i)
+        log << "| ";
+
+      log << base::StringPrintf("'%c', %s", phase, name);
+
+      if (phase == TRACE_EVENT_PHASE_END)
+        log << base::StringPrintf(" (%.3f ms)", duration.InMillisecondsF());
+
+      VLOG(0) << log.str() << "\e[0;m";
+    }
+
     logged_events_->AddEvent(TraceEvent(thread_id,
         now, phase, category_group_enabled, name, id,
         num_args, arg_names, arg_types, arg_values,
@@ -1051,6 +1112,9 @@ void TraceLog::AddTraceEventWithThreadIdAndTimestamp(
     event_callback_copy = event_callback_;
   }  // release lock
 
+  if (phase == TRACE_EVENT_PHASE_BEGIN && trace_options_ & ECHO_TO_VLOG)
+    thread_event_start_times_[thread_id].push(timestamp);
+
   notifier.SendNotificationIfAny();
   if (event_callback_copy != NULL) {
     event_callback_copy(phase, category_group_enabled, name, id,