[Fuchsia] Routes timeline events to Fuchsia's tracing app

runtime/vm/timeline.h

Index: runtime/vm/timeline.h
diff --git a/runtime/vm/timeline.h b/runtime/vm/timeline.h
index c7c6016693bd9489884608cbbb4e415f3cd322a1..0abf0254d91b0cdca4c8dda9dccb7fbfae28cc9a 100644
--- a/runtime/vm/timeline.h
+++ b/runtime/vm/timeline.h
@@ -318,6 +318,10 @@ class TimelineEvent {
   // Returns the number of bytes written into |buffer|.
   intptr_t PrintSystrace(char* buffer, intptr_t buffer_size);
 
+#if defined(HOST_OS_FUCHSIA)
+  void EmitFuchsiaEvent();
+#endif
+
  private:
   void FreeArguments();
 
@@ -386,6 +390,7 @@ class TimelineEvent {
   friend class TimelineEventRingRecorder;
   friend class TimelineEventStartupRecorder;
   friend class TimelineEventSystraceRecorder;
+  friend class TimelineEventFuchsiaRecorder;
   friend class TimelineStream;
   friend class TimelineTestHelper;
   DISALLOW_COPY_AND_ASSIGN(TimelineEvent);
@@ -433,6 +438,10 @@ class TimelineEventScope : public StackResource {
 
   const char* label() const { return label_; }
 
+  TimelineEventArgument* arguments() const { return arguments_; }
+
+  intptr_t arguments_length() const { return arguments_length_; }
+
   TimelineStream* stream() const { return stream_; }
 
   virtual ~TimelineEventScope();
@@ -560,6 +569,7 @@ class TimelineEventBlock {
   friend class TimelineEventRingRecorder;
   friend class TimelineEventStartupRecorder;
   friend class TimelineEventSystraceRecorder;
+  friend class TimelineEventFuchsiaRecorder;
   friend class TimelineTestHelper;
   friend class JSONStream;
 
@@ -735,6 +745,25 @@ class TimelineEventSystraceRecorder : public TimelineEventFixedBufferRecorder {
 };
 
 
+#if defined(HOST_OS_FUCHSIA)
+// A recorder that sends events to Fuchsia's tracing app. Events are also stored
+// in a buffer of fixed capacity. When the buffer is full, new events overwrite
+// old events.
+// See: https://fuchsia.googlesource.com/tracing/+/HEAD/docs/usage_guide.md
+class TimelineEventFuchsiaRecorder : public TimelineEventFixedBufferRecorder {
+ public:
+  explicit TimelineEventFuchsiaRecorder(intptr_t capacity = kDefaultCapacity);
+  virtual ~TimelineEventFuchsiaRecorder() {}
+
+  const char* name() const { return "Fuchsia"; }
+
+ protected:
+  TimelineEventBlock* GetNewBlockLocked();
+  void CompleteEvent(TimelineEvent* event);
+};
+#endif  // defined(HOST_OS_FUCHSIA)
+
+
 // A recorder that stores events in a buffer of fixed capacity. When the buffer
 // is full, new events are dropped.
 class TimelineEventStartupRecorder : public TimelineEventFixedBufferRecorder {