Added UMA metrics for ChromeOS first-run UI.

chrome/browser/chromeos/first_run/step.cc

Index: chrome/browser/chromeos/first_run/step.cc
diff --git a/chrome/browser/chromeos/first_run/step.cc b/chrome/browser/chromeos/first_run/step.cc
index a26950c8667f72a6ec04dbc19e2e1e63a22e2aa8..b5432eea7252752e0d86096f13417b4fa5bef905 100644
--- a/chrome/browser/chromeos/first_run/step.cc
+++ b/chrome/browser/chromeos/first_run/step.cc
@@ -4,11 +4,36 @@
 
 #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 {
 
@@ -20,19 +45,45 @@ Step::Step(const std::string& name,
       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.TimeSpentOnStep" + ToCamelCase(name());
+  // Equivalent to using UMA_HISTOGRAM_CUSTOM_TIMES with 50 buckets on range
+  // [100ms, 3 min.]. UMA_HISTOGRAM_CUSTOM_TIMES can not be used here, because
+  // |histogram_name| is calculated dynamically and changes from call to call.
+  base::HistogramBase* histogram = base::Histogram::FactoryTimeGet(
+      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