Record user actions for long-press follow-on actions.

ui/touch_selection/touch_selection_controller.cc

 // Copyright 2014 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 "ui/touch_selection/touch_selection_controller.h"
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
+#include "base/metrics/user_metrics.h"
 
 namespace ui {
 namespace {
 
 gfx::Vector2dF ComputeLineOffsetFromBottom(const SelectionBound& bound) {
   gfx::Vector2dF line_offset =
       gfx::ScaleVector2d(bound.edge_top() - bound.edge_bottom(), 0.5f);
   // An offset of 8 DIPs is sufficient for most line sizes. For small lines,
   // using half the line height avoids synthesizing a point on a line above
   // (or below) the intended line.
@@ skipping 357 matching lines @@
     anchor_drag_to_selection_start_ =
         (drag_position - GetStartPosition()).LengthSquared() <
         (drag_position - GetEndPosition()).LengthSquared();
   }
 
   gfx::PointF base = GetStartPosition() + GetStartLineOffset();
   gfx::PointF extent = GetEndPosition() + GetEndLineOffset();
   if (anchor_drag_to_selection_start_)
     std::swap(base, extent);
 
+  // If this is the first drag, log an action to allow user action sequencing.
+  if (!selection_handle_dragged_) {
+    base::RecordAction(base::UserMetricsAction("MobileSelectionChanged"));

[mohsen, 2016/05/12 17:27:44]

nit: By "Mobile" do you mean Android? Can we use a more general name that is
also meaningful on desktop?

nit2: Curly braces are not necessary here.

[Donn Denman, 2016/05/12 17:37:46]

Good point -- changed to SelectionChanged.
Done.

+  }
   selection_handle_dragged_ = true;
 
   // When moving the handle we want to move only the extent point. Before doing
   // so we must make sure that the base point is set correctly.
   client_->SelectBetweenCoordinates(base, extent);
   client_->OnSelectionEvent(SELECTION_HANDLE_DRAG_STARTED);
 }
 
 void TouchSelectionController::OnDragUpdate(
     const TouchSelectionDraggable& draggable,
@@ skipping 293 matching lines @@
     base::TimeDelta duration = base::TimeTicks::Now() - selection_start_time_;
     UMA_HISTOGRAM_CUSTOM_TIMES("Event.TouchSelection.WasDraggedDuration",
                                duration,
                                base::TimeDelta::FromMilliseconds(500),
                                base::TimeDelta::FromSeconds(60),
                                60);
   }
 }
 
 }  // namespace ui