Merge pull request #2611 from jamesr/better_tracing

Improve tracing in graphics stack, esp on Mojo

sky/shell/gpu/mojo/rasterizer_mojo.cc

@@ -17,7 +17,7 @@ namespace shell {
 namespace {
 
 void DidEcho(void* context) {
-  TRACE_EVENT_ASYNC_END0("flutter", "DidEcho", context);
+  TRACE_EVENT_ASYNC_END0("flutter", "MGLEcho", context);
   Rasterizer::DrawCallback* callback = static_cast<Rasterizer::DrawCallback*>(context);
   callback->Run();
   delete callback;
@@ -69,6 +69,7 @@ void RasterizerMojo::Draw(uint64_t layer_tree_ptr,
       reinterpret_cast<flow::LayerTree*>(layer_tree_ptr));
 
   if (!scene_ || !gl_state_ || gl_state_->gl_context->is_lost()) {
+    TRACE_EVENT_INSTANT0("flutter", "RasterizerMojo::Draw error one", TRACE_EVENT_SCOPE_THREAD);
     callback.Run();
     return;
   }
@@ -78,6 +79,7 @@ void RasterizerMojo::Draw(uint64_t layer_tree_ptr,
   size.height = layer_tree->frame_size().height();
 
   if (size.width <= 0 || size.height <= 0.0) {
+    TRACE_EVENT_INSTANT0("flutter", "RasterizerMojo::Draw empty frame size", TRACE_EVENT_SCOPE_THREAD);
     callback.Run();
     return;
   }

sky/shell/ui/animator.cc

@@ -38,7 +38,9 @@ void Animator::RequestFrame() {
 
   DCHECK(!did_defer_frame_request_);
   outstanding_requests_++;
+  TRACE_COUNTER1("flutter", "outstanding_requests_", outstanding_requests_);
   if (outstanding_requests_ >= kPipelineDepth) {
+    TRACE_EVENT_INSTANT1("flutter", "Frame request deferred", TRACE_EVENT_SCOPE_THREAD, "outstanding_requests_", outstanding_requests_);
     did_defer_frame_request_ = true;
     return;
   }
@@ -116,6 +118,7 @@ void Animator::Render(std::unique_ptr<flow::LayerTree> layer_tree) {
 void Animator::OnFrameComplete() {
   DCHECK(outstanding_requests_ > 0);
   --outstanding_requests_;
+  TRACE_COUNTER1("flutter", "outstanding_requests_", outstanding_requests_);
   if (paused_)
     return;
 
@@ -144,6 +147,7 @@ void Animator::Reset() {
   weak_factory_.InvalidateWeakPtrs();
 
   outstanding_requests_ = 0;
+  TRACE_COUNTER1("flutter", "outstanding_requests_", outstanding_requests_);
   did_defer_frame_request_ = false;
   engine_requested_frame_ = false;
   paused_ = false;