Track flow id (flutter#7826)

GaryQian · web-flow · commit a8aa1ee060ac · 2019-02-14T12:30:29.000-08:00
(Authored by @nathanrogersgoogle )
diff --git a/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm b/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm
@@ -10,6 +10,7 @@
 
 #include "flutter/fml/message_loop.h"
 #include "flutter/fml/platform/darwin/platform_version.h"
+#include "flutter/fml/trace_event.h"
 #include "flutter/shell/common/engine.h"
 #include "flutter/shell/common/platform_view.h"
 #include "flutter/shell/common/shell.h"
@@ -61,6 +62,8 @@ @implementation FlutterEngine {
 
   int64_t _nextTextureId;
 
+  uint64_t _nextPointerFlowId;
+
   BOOL _allowHeadlessExecution;
 }
 
@@ -117,12 +120,15 @@ - (void)updateViewportMetrics:(blink::ViewportMetrics)viewportMetrics {
 }
 
 - (void)dispatchPointerDataPacket:(std::unique_ptr<blink::PointerDataPacket>)packet {
-  self.shell.GetTaskRunners().GetUITaskRunner()->PostTask(
-      fml::MakeCopyable([engine = self.shell.GetEngine(), packet = std::move(packet)] {
+  TRACE_EVENT0("flutter", "dispatchPointerDataPacket");
+  TRACE_FLOW_BEGIN("flutter", "PointerEvent", _nextPointerFlowId);
+  self.shell.GetTaskRunners().GetUITaskRunner()->PostTask(fml::MakeCopyable(
+      [engine = self.shell.GetEngine(), packet = std::move(packet), flow_id = _nextPointerFlowId] {
         if (engine) {
-          engine->DispatchPointerDataPacket(*packet);
+          engine->DispatchPointerDataPacket(*packet, flow_id);
         }
       }));
+  _nextPointerFlowId++;
 }
 
 - (fml::WeakPtr<shell::PlatformView>)platformView {
