Added UMA metrics for ChromeOS first-run UI.

chrome/browser/chromeos/first_run/step.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 "chrome/browser/chromeos/first_run/step.h"
 
+#include <cctype>
+
 #include "ash/first_run/first_run_helper.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/metrics/histogram.h"
 #include "chrome/browser/ui/webui/chromeos/first_run/first_run_actor.h"
 #include "ui/gfx/size.h"
 #include "ui/views/widget/widget.h"
 
+namespace {
+
+// Converts from "with-dashes-names" to "WithDashesNames".
+std::string ToCamelCase(const std::string& name) {
+  std::string result;
+  bool next_to_upper = true;
+  for (size_t i = 0; i < name.length(); ++i) {
+    if (name[i] == '-') {
+      next_to_upper = true;
+    } else if (next_to_upper) {
+      result.push_back(std::toupper(name[i]));
+      next_to_upper = false;
+    } else {
+      result.push_back(name[i]);
+    }
+  }
+  return result;
+}
+
+}  // namespace
+
 namespace chromeos {
 namespace first_run {
 
 Step::Step(const std::string& name,
            ash::FirstRunHelper* shell_helper,
            FirstRunActor* actor)
     : name_(name),
       shell_helper_(shell_helper),
       actor_(actor) {
 }
 
-Step::~Step() {}
+Step::~Step() { RecordCompletion(); }
+
+void Step::Show() {
+  show_time_ = base::Time::Now();
+  DoShow();
+}
 
 void Step::OnBeforeHide() {
   actor()->RemoveBackgroundHoles();
+  DoOnBeforeHide();
 }
 
 void Step::OnAfterHide() {
+  RecordCompletion();
+  DoOnAfterHide();
 }
 
 gfx::Size Step::GetOverlaySize() const {
   return shell_helper()->GetOverlayWidget()->GetWindowBoundsInScreen().size();
 }
 
+void Step::RecordCompletion() {
+  if (show_time_.is_null())
+    return;
+  std::string histogram_name =
+      "CrosFirstRun.TimeSpentOn" + ToCamelCase(name()) + "Step";
+  base::HistogramBase* histogram = base::Histogram::FactoryTimeGet(

[Alexei Svitkine (slow), 2014/01/15 16:02:38]

Nit: Maybe add a comment with an UMA macro declaration that this expanded form
corresponds to.

[dzhioev (left Google), 2014/01/15 22:12:54]

Done. Added comment.

+      histogram_name,
+      base::TimeDelta::FromMilliseconds(100),
+      base::TimeDelta::FromMinutes(3),
+      50,
+      base::HistogramBase::kUmaTargetedHistogramFlag);
+  histogram->AddTime(base::Time::Now() - show_time_);
+  show_time_ = base::Time();
+}
+
 }  // namespace first_run
 }  // namespace chromeos