Convert enum to enum class for views::SliderChangeReason

Use enum class instead of enum for views::SliderChangeReason.
enum class is more type safety.

Bug: 940736
Change-Id: I396a74e79cdf6da52163d875fcceffa20920968f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2128033Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Hwanseung Lee <hs1217.lee@samsung.com>
Cr-Commit-Position: refs/heads/master@{#755194}

ash/system/audio/unified_volume_slider_controller.cc

@@ -50,7 +50,7 @@ void UnifiedVolumeSliderController::SliderValueChanged(
     float value,
     float old_value,
     views::SliderChangeReason reason) {
-  if (reason != views::VALUE_CHANGED_BY_USER)
+  if (reason != views::SliderChangeReason::kByUser)
     return;
 
   const int level = value * 100;

ash/system/brightness/unified_brightness_slider_controller.cc

@@ -43,7 +43,7 @@ void UnifiedBrightnessSliderController::SliderValueChanged(
     float value,
     float old_value,
     views::SliderChangeReason reason) {
-  if (reason != views::VALUE_CHANGED_BY_USER)
+  if (reason != views::SliderChangeReason::kByUser)
     return;
 
   BrightnessControlDelegate* brightness_control_delegate =

ui/views/controls/slider.cc

@@ -69,7 +69,7 @@ float Slider::GetValue() const {
 }
 
 void Slider::SetValue(float value) {
-  SetValueInternal(value, VALUE_CHANGED_BY_API);
+  SetValueInternal(value, SliderChangeReason::kByApi);
 }
 
 bool Slider::GetEnableAccessibilityEvents() const {
@@ -180,7 +180,7 @@ void Slider::MoveButtonTo(const gfx::Point& point) {
                    : point.x() - inset.left() - initial_button_offset_;
   SetValueInternal(
       static_cast<float>(amount) / (width() - inset.width() - kThumbWidth),
-      VALUE_CHANGED_BY_USER);
+      SliderChangeReason::kByUser);
 }
 
 void Slider::OnSliderDragStarted() {
@@ -240,7 +240,7 @@ bool Slider::OnKeyPressed(const ui::KeyEvent& event) {
       return false;
   }
   SetValueInternal(value_ + direction * keyboard_increment_,
-                   VALUE_CHANGED_BY_USER);
+                   SliderChangeReason::kByUser);
   return true;
 }
 

ui/views/controls/slider.h

@@ -22,9 +22,9 @@ class SliderTestApi;
 
 class Slider;
 
-enum SliderChangeReason {
-  VALUE_CHANGED_BY_USER,  // value was changed by the user (by clicking, e.g.)
-  VALUE_CHANGED_BY_API,   // value was changed by a call to SetValue.
+enum class SliderChangeReason {
+  kByUser,  // value was changed by the user (e.g. by clicking)
+  kByApi,   // value was changed by a call to SetValue.
 };
 
 class VIEWS_EXPORT SliderListener {