chromeos: adds trace events for resizing top-levels

This makes it easier to correlate changes in ash with that in the browser.

BUG=951015
TEST=none

Change-Id: I3d0ce9f15a69cd83f837b2ea10f6dc1f1c0f8d56
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1562754Reviewed-by: Jun Mukai <mukai@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#649709}

services/ws/client_root.cc

@@ -8,6 +8,7 @@
 #include "base/callback_forward.h"
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
+#include "base/trace_event/trace_event.h"
 #include "components/viz/common/surfaces/surface_info.h"
 #include "components/viz/host/host_frame_sink_manager.h"
 #include "services/ws/client_change.h"
@@ -331,6 +332,9 @@ void ClientRoot::HandleBoundsOrScaleFactorChange() {
 void ClientRoot::NotifyClientOfNewBounds() {
   last_bounds_ = GetBoundsToSend(window_);
   auto id = ProxyWindow::GetMayBeNull(window_)->local_surface_id_allocation();
+  TRACE_EVENT_WITH_FLOW0("ui", "ClientRoot::NotifyClientOfNewBounds",
+                         id->local_surface_id().hash(),
+                         TRACE_EVENT_FLAG_FLOW_OUT);
   window_tree_->window_tree_client_->OnWindowBoundsChanged(
       window_tree_->TransportIdForWindow(window_), last_bounds_,
       ProxyWindow::GetMayBeNull(window_)->local_surface_id_allocation());

ui/aura/mus/window_tree_client.cc

@@ -21,6 +21,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/threading/thread.h"
+#include "base/trace_event/trace_event.h"
 #include "cc/base/switches.h"
 #include "components/discardable_memory/client/client_discardable_shared_memory_manager.h"
 #include "mojo/public/cpp/bindings/map.h"
@@ -1224,6 +1225,14 @@ void WindowTreeClient::OnWindowBoundsChanged(
   if (!window)
     return;
 
+  if (IsRoot(window)) {
+    TRACE_EVENT_WITH_FLOW0(
+        "ui", "ClientRoot::NotifyClientOfNewBounds",
+        local_surface_id_allocation->local_surface_id().hash(),
+        TRACE_EVENT_FLAG_FLOW_IN);
+  }
+  TRACE_EVENT0("ui", "WindowTreeClient::OnWindowBoundsChanged");
+
   InFlightBoundsChange new_change(this, window, new_bounds,
                                   /* from_server */ true,
                                   local_surface_id_allocation);