Remove LatencyInfo::sequence_number. (May break metrics).

cc/trees/latency_info_swap_promise_monitor.cc

 // Copyright 2013 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/trees/latency_info_swap_promise_monitor.h"
 
 #include <stdint.h>
 
 #include "base/threading/platform_thread.h"
 #include "cc/output/latency_info_swap_promise.h"
 #include "cc/trees/layer_tree_host_impl.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "cc/trees/swap_promise_manager.h"
 
 namespace {
 
 bool AddRenderingScheduledComponent(ui::LatencyInfo* latency_info,
                                     bool on_main) {
   ui::LatencyComponentType type =
       on_main ? ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_MAIN_COMPONENT
               : ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT;
   if (latency_info->FindLatency(type, 0, nullptr))
     return false;
-  latency_info->AddLatencyNumber(type, 0, 0);
+  latency_info->AddLatencyNumber(type, 0);
   return true;
 }
 
 bool AddForwardingScrollUpdateToMainComponent(ui::LatencyInfo* latency_info) {
   if (latency_info->FindLatency(
           ui::INPUT_EVENT_LATENCY_FORWARD_SCROLL_UPDATE_TO_MAIN_COMPONENT, 0,
           nullptr))
     return false;
   latency_info->AddLatencyNumber(
-      ui::INPUT_EVENT_LATENCY_FORWARD_SCROLL_UPDATE_TO_MAIN_COMPONENT, 0,
+      ui::INPUT_EVENT_LATENCY_FORWARD_SCROLL_UPDATE_TO_MAIN_COMPONENT,
       latency_info->trace_id());
   return true;
 }
 
 }  // namespace
 
 namespace cc {
 
 LatencyInfoSwapPromiseMonitor::LatencyInfoSwapPromiseMonitor(
     ui::LatencyInfo* latency,
@@ skipping 21 matching lines @@
     // measurement of the time to the next SwapBuffers(). The swap
     // promise is pinned so that it is not interrupted by new incoming
     // activations (which would otherwise break the swap promise).
     layer_tree_host_impl_->active_tree()->QueuePinnedSwapPromise(
         std::move(swap_promise));
   }
 }
 
 void LatencyInfoSwapPromiseMonitor::OnForwardScrollUpdateToMainThreadOnImpl() {
   if (AddForwardingScrollUpdateToMainComponent(latency_)) {
-    int64_t new_sequence_number = 0;
-    for (ui::LatencyInfo::LatencyMap::const_iterator it =
-             latency_->latency_components().begin();
-         it != latency_->latency_components().end(); ++it) {
-      if (it->first.first == ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT) {
-        new_sequence_number =
-            ((static_cast<int64_t>(base::PlatformThread::CurrentId()) << 32) ^
-             (reinterpret_cast<uint64_t>(this) << 32)) |
-            (it->second.sequence_number & 0xffffffff);
-        if (new_sequence_number == it->second.sequence_number)
-          return;
-        break;
-      }
-    }
-    if (!new_sequence_number)
-      return;

[tdresser, 2017/06/08 18:36:44]

This is a material change. 

I think what's happening here is that we're returning early if we've already
sent the event to this main thread.

I'm not sure when this could happen though...

     ui::LatencyInfo new_latency;
     new_latency.AddLatencyNumberWithTraceName(
         ui::LATENCY_BEGIN_SCROLL_LISTENER_UPDATE_MAIN_COMPONENT, 0,
-        new_sequence_number, "ScrollUpdate");
+        "ScrollUpdate");
     new_latency.CopyLatencyFrom(
         *latency_,
         ui::INPUT_EVENT_LATENCY_FORWARD_SCROLL_UPDATE_TO_MAIN_COMPONENT);
     std::unique_ptr<SwapPromise> swap_promise(
         new LatencyInfoSwapPromise(new_latency));
     layer_tree_host_impl_->QueueSwapPromiseForMainThreadScrollUpdate(
         std::move(swap_promise));
   }
 }
 
 }  // namespace cc