Record Timeline to Android Systrace

runtime/vm/timeline.h

Index: runtime/vm/timeline.h
diff --git a/runtime/vm/timeline.h b/runtime/vm/timeline.h
index d91e9090189a519f0e2172072d779ffd74140556..851113f8ca3f5caa578cdbd937b71a2b5faa3ef3 100644
--- a/runtime/vm/timeline.h
+++ b/runtime/vm/timeline.h
@@ -342,6 +342,9 @@ class TimelineEvent {
     state_ = OwnsLabelBit::update(owns_label, state_);
   }
 
+  // Returns the number of bytes written into |buffer|.
+  intptr_t PrintSystrace(char* buffer, intptr_t buffer_size);
+
  private:
   void FreeArguments();
 
@@ -413,6 +416,7 @@ class TimelineEvent {
   friend class TimelineEventEndlessRecorder;
   friend class TimelineEventRingRecorder;
   friend class TimelineEventStartupRecorder;
+  friend class TimelineEventSystraceRecorder;
   friend class TimelineStream;
   friend class TimelineTestHelper;
   DISALLOW_COPY_AND_ASSIGN(TimelineEvent);
@@ -622,6 +626,7 @@ class TimelineEventBlock {
   friend class TimelineEventEndlessRecorder;
   friend class TimelineEventRingRecorder;
   friend class TimelineEventStartupRecorder;
+  friend class TimelineEventSystraceRecorder;
   friend class TimelineTestHelper;
   friend class JSONStream;
 
@@ -786,6 +791,28 @@ class TimelineEventRingRecorder : public TimelineEventFixedBufferRecorder {
 };
 
 
+// A recorder that writes events to Android Systrace. Events are also stored in
+// a buffer of fixed capacity. When the buffer is full, new events overwrite
+// old events.
+class TimelineEventSystraceRecorder
+    : public TimelineEventFixedBufferRecorder {
+ public:
+  explicit TimelineEventSystraceRecorder(intptr_t capacity = kDefaultCapacity);
+
+  ~TimelineEventSystraceRecorder();
+
+  const char* name() const {
+    return "Systrace";
+  }
+
+ protected:
+  TimelineEventBlock* GetNewBlockLocked();
+  void CompleteEvent(TimelineEvent* event);
+
+  int systrace_fd_;

[Chinmay, 2016/09/08 17:58:11]

Should this be private? Along with the usual `DISALLOW_COPY_AND_ASSIGN`
decoration on the class.

[Cutch, 2016/09/08 18:06:10]

The base class has the decoration.

+};
+
+
 // A recorder that stores events in a buffer of fixed capacity. When the buffer
 // is full, new events are dropped.
 class TimelineEventStartupRecorder : public TimelineEventFixedBufferRecorder {