Make button beside brightness slider unclickable.

The button on the right of the brightness sldier is no-op, so we should
call SetEnabled(false).
In order to do this, this CL changed disabled color of the buton icon.

TEST=manual
BUG=854148

Change-Id: I1f0e98540a86696351135275be8946b7250cbc12
Reviewed-on: https://chromium-review.googlesource.com/1107423Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568752}

ash/system/brightness/unified_brightness_view.cc

@@ -18,6 +18,8 @@ UnifiedBrightnessView::UnifiedBrightnessView(
                         kSystemMenuBrightnessIcon,
                         IDS_ASH_STATUS_TRAY_BRIGHTNESS),
       model_(model) {
+  button()->SetEnabled(false);
+
   model_->AddObserver(this);
   OnDisplayBrightnessChanged(false /* by_user */);
 }

ash/system/unified/top_shortcut_button.cc

@@ -19,13 +19,17 @@ namespace ash {
 TopShortcutButton::TopShortcutButton(views::ButtonListener* listener,
                                      const gfx::VectorIcon& icon,
                                      int accessible_name_id)
-    : views::ImageButton(listener) {
-  SetPreferredSize(gfx::Size(kTrayItemSize, kTrayItemSize));
-
+    : TopShortcutButton(listener, accessible_name_id) {
   SetImage(views::Button::STATE_NORMAL,
            gfx::CreateVectorIcon(icon, kUnifiedMenuIconColor));
   SetImage(views::Button::STATE_DISABLED,
            gfx::CreateVectorIcon(icon, kUnifiedMenuIconColorDisabled));
+}
+
+TopShortcutButton::TopShortcutButton(views::ButtonListener* listener,
+                                     int accessible_name_id)
+    : views::ImageButton(listener) {
+  SetPreferredSize(gfx::Size(kTrayItemSize, kTrayItemSize));
 
   SetImageAlignment(ALIGN_CENTER, ALIGN_MIDDLE);
   SetTooltipText(l10n_util::GetStringUTF16(accessible_name_id));

ash/system/unified/top_shortcut_button.h

@@ -18,6 +18,7 @@ class TopShortcutButton : public views::ImageButton {
   TopShortcutButton(views::ButtonListener* listener,
                     const gfx::VectorIcon& icon,
                     int accessible_name_id);
+  TopShortcutButton(views::ButtonListener* listener, int accessible_name_id);
   ~TopShortcutButton() override;
 
   // views::ImageButton:

ash/system/unified/unified_slider_view.cc

@@ -47,7 +47,9 @@ void ReadOnlySlider::OnGestureEvent(ui::GestureEvent* event) {}
 UnifiedSliderButton::UnifiedSliderButton(views::ButtonListener* listener,
                                          const gfx::VectorIcon& icon,
                                          int accessible_name_id)
-    : TopShortcutButton(listener, icon, accessible_name_id) {}
+    : TopShortcutButton(listener, accessible_name_id) {
+  SetVectorIcon(icon);
+}
 
 UnifiedSliderButton::~UnifiedSliderButton() = default;