Small adjustment of tracing for discarded retro frames.

cc/scheduler/scheduler.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/scheduler/scheduler.h"
 
 #include <algorithm>
 #include "base/auto_reset.h"
 #include "base/debug/trace_event.h"
 #include "base/debug/trace_event_argument.h"
@@ skipping 440 matching lines @@
 
   // Discard expired BeginRetroFrames
   // Today, we should always end up with at most one un-expired BeginRetroFrame
   // because deadlines will not be greater than the next frame time. We don't
   // DCHECK though because some systems don't always have monotonic timestamps.
   // TODO(brianderson): In the future, long deadlines could result in us not
   // draining the queue if we don't catch up. If we consistently can't catch
   // up, our fallback should be to lower our frame rate.
   base::TimeTicks now = Now();
   base::TimeDelta draw_duration_estimate = client_->DrawDurationEstimate();
-  while (!begin_retro_frame_args_.empty() &&
-         now > AdjustedBeginImplFrameDeadline(begin_retro_frame_args_.front(),
-                                              draw_duration_estimate)) {
-    TRACE_EVENT1("cc",
-                 "Scheduler::BeginRetroFrame discarding",
-                 "frame_time",
-                 begin_retro_frame_args_.front().frame_time);
+  while (!begin_retro_frame_args_.empty()) {
+    base::TimeTicks adjusted_deadline = AdjustedBeginImplFrameDeadline(
+        begin_retro_frame_args_.front(), draw_duration_estimate);
+    if (now < adjusted_deadline)

[Sami, 2014/09/18 10:22:34]

nit: This should be "<=" to match the previous behavior.

+      break;
+
+    TRACE_EVENT_INSTANT2("cc",
+                         "Scheduler::BeginRetroFrame discarding",
+                         TRACE_EVENT_SCOPE_THREAD,
+                         "deadline - now",
+                         (adjusted_deadline - now).InMicroseconds(),
+                         "BeginFrameArgs",
+                         begin_retro_frame_args_.front().AsValue());
     begin_retro_frame_args_.pop_front();
   }
 
   if (begin_retro_frame_args_.empty()) {
     DCHECK(settings_.throttle_frame_production);
     TRACE_EVENT_INSTANT0("cc",
                          "Scheduler::BeginRetroFrames all expired",
                          TRACE_EVENT_SCOPE_THREAD);
   } else {
     BeginImplFrame(begin_retro_frame_args_.front());
@@ skipping 289 matching lines @@
 }
 
 bool Scheduler::IsBeginMainFrameSentOrStarted() const {
   return (state_machine_.commit_state() ==
               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_SENT ||
           state_machine_.commit_state() ==
               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED);
 }
 
 }  // namespace cc