input: Change how synthesized events are dispatched in telemetry tests.

content/browser/renderer_host/input/synthetic_gesture_controller.cc

Index: content/browser/renderer_host/input/synthetic_gesture_controller.cc
diff --git a/content/browser/renderer_host/input/synthetic_gesture_controller.cc b/content/browser/renderer_host/input/synthetic_gesture_controller.cc
index 9e5bc84403eb18e01f09e43b26b9db51fbd20211..6b2155ec495168a5f17e9df9ae79acdcc1b5f6da 100644
--- a/content/browser/renderer_host/input/synthetic_gesture_controller.cc
+++ b/content/browser/renderer_host/input/synthetic_gesture_controller.cc
@@ -6,6 +6,7 @@
 
 #include <utility>
 
+#include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/trace_event.h"
 #include "content/browser/renderer_host/input/synthetic_gesture_target.h"
 #include "content/common/input/synthetic_smooth_scroll_gesture_params.h"
@@ -15,8 +16,11 @@
 namespace content {
 
 SyntheticGestureController::SyntheticGestureController(
-    std::unique_ptr<SyntheticGestureTarget> gesture_target)
-    : gesture_target_(std::move(gesture_target)) {}
+    std::unique_ptr<SyntheticGestureTarget> gesture_target,
+    BeginFrameRequestCallback begin_frame_callback)
+    : gesture_target_(std::move(gesture_target)),
+      begin_frame_callback_(std::move(begin_frame_callback)),
+      weak_ptr_factory_(this) {}
 
 SyntheticGestureController::~SyntheticGestureController() {}
 
@@ -34,51 +38,44 @@ void SyntheticGestureController::QueueSyntheticGesture(
     StartGesture(*pending_gesture_queue_.FrontGesture());
 }
 
-void SyntheticGestureController::Flush(base::TimeTicks timestamp) {
+void SyntheticGestureController::OnBeginFrame() {
+  // TODO(sad): Instead of dispatching the events immediately, dispatch after an
+  // offset.
+  DispatchNextEvent();
+}
+
+bool SyntheticGestureController::DispatchNextEvent(base::TimeTicks timestamp) {
   TRACE_EVENT0("input", "SyntheticGestureController::Flush");
   if (pending_gesture_queue_.IsEmpty())
-    return;
-
-  if (pending_gesture_result_)

[dtapuska, 2017/05/16 14:39:41]

Doesn't removing the pending_gesture_result_ not change the behavior of this
method? Should pending_gesture_result_ be checked in OnBeginFrame() ?

I'm wondering about the case where a gesture has been sent.

[dtapuska, 2017/05/16 14:40:52]

Ugh; no this submitted the wrong comment.  I looked over it more; disregard that
comment by my new one was: Can pending_gesture_result_ be removed?

[sadrul, 2017/05/16 17:35:05]

Yep, done.

-    return;
+    return false;
 
   SyntheticGesture* gesture = pending_gesture_queue_.FrontGesture();

[dtapuska, 2017/05/16 14:39:41]

Do we need this variable on the stack? I feel someone might want to use it after
its storage is removed. Looks to only be used in one spot so we should be able
to just get rid of the variable reference.

[sadrul, 2017/05/16 17:35:05]

Done.

   SyntheticGesture::Result result =
       gesture->ForwardInputEvents(timestamp, gesture_target_.get());
 
   if (result == SyntheticGesture::GESTURE_RUNNING) {
-    gesture_target_->SetNeedsFlush();
-    return;
+    begin_frame_callback_.Run(
+        base::BindOnce(&SyntheticGestureController::OnBeginFrame,
+                       weak_ptr_factory_.GetWeakPtr()));
+    return true;
   }
 
-  // It's possible that all events generated by the gesture have been fully
-  // dispatched at this point, in which case |OnDidFlushInput()| was called
-  // before |pending_gesture_result_| was initialized. Requesting another flush
-  // will trigger the necessary gesture-ending call to |OnDidFlushInput()|.
-  pending_gesture_result_.reset(new SyntheticGesture::Result(result));
-  gesture_target_->SetNeedsFlush();
-}
-
-void SyntheticGestureController::OnDidFlushInput() {
-  if (!pending_gesture_result_)
-    return;
-
-  DCHECK(!pending_gesture_queue_.IsEmpty());
-  auto pending_gesture_result = std::move(pending_gesture_result_);
   StopGesture(*pending_gesture_queue_.FrontGesture(),
-              pending_gesture_queue_.FrontCallback(),
-              *pending_gesture_result);
+              pending_gesture_queue_.FrontCallback(), result);
   pending_gesture_queue_.Pop();
-
-  if (!pending_gesture_queue_.IsEmpty())
-    StartGesture(*pending_gesture_queue_.FrontGesture());
+  if (pending_gesture_queue_.IsEmpty())
+    return false;
+  StartGesture(*pending_gesture_queue_.FrontGesture());
+  return true;
 }
 
 void SyntheticGestureController::StartGesture(const SyntheticGesture& gesture) {
   TRACE_EVENT_ASYNC_BEGIN0("input,benchmark",
                            "SyntheticGestureController::running",
                            &gesture);
-  gesture_target_->SetNeedsFlush();
+  begin_frame_callback_.Run(
+      base::BindOnce(&SyntheticGestureController::OnBeginFrame,
+                     weak_ptr_factory_.GetWeakPtr()));
 }
 
 void SyntheticGestureController::StopGesture(