Implements a display scale tray setting behind a chrome switch

ash/system/display_scale/scale_view.cc

Index: ash/system/display_scale/scale_view.cc
diff --git a/ash/system/display_scale/scale_view.cc b/ash/system/display_scale/scale_view.cc
new file mode 100644
index 0000000000000000000000000000000000000000..8a80128ce79177f55d044acb96c7da3e0dcac774
--- /dev/null
+++ b/ash/system/display_scale/scale_view.cc
@@ -0,0 +1,100 @@
+// Copyright 2017 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 "ash/system/display_scale/scale_view.h"
+
+#include <algorithm>
+
+#include "ash/shell.h"
+#include "ash/strings/grit/ash_strings.h"
+#include "ash/system/tray/actionable_view.h"
+#include "ash/system/tray/system_tray_item.h"
+#include "ash/system/tray/tray_constants.h"
+#include "ash/system/tray/tray_popup_utils.h"
+#include "ash/system/tray/tri_view.h"
+#include "base/command_line.h"
+#include "base/strings/stringprintf.h"
+#include "base/strings/utf_string_conversions.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/display/display.h"
+#include "ui/display/manager/display_manager.h"
+#include "ui/native_theme/native_theme.h"
+#include "ui/views/background.h"
+#include "ui/views/border.h"
+#include "ui/views/controls/image_view.h"
+#include "ui/views/controls/label.h"
+#include "ui/views/controls/slider.h"
+#include "ui/views/layout/fill_layout.h"
+
+namespace ash {
+namespace tray {
+
+ScaleView::ScaleView(SystemTrayItem* owner, bool is_default_view)
+    : owner_(owner),
+      tri_view_(TrayPopupUtils::CreateMultiTargetRowView()),
+      more_button_(nullptr),
+      label_(nullptr),
+      slider_(nullptr),
+      is_default_view_(is_default_view) {
+  SetLayoutManager(new views::FillLayout);
+  AddChildView(tri_view_);
+
+  label_ = new views::Label(base::UTF8ToUTF16(base::StringPrintf(
+      "%.2f", display::Display::GetForcedDeviceScaleFactor())));
+  tri_view_->AddView(TriView::Container::START, label_);
+
+  slider_ = TrayPopupUtils::CreateSlider(this);
+  slider_->SetValue((display::Display::GetForcedDeviceScaleFactor() - 1.f) / 2);
+  slider_->SetAccessibleName(
+      l10n_util::GetStringUTF16(IDS_ASH_STATUS_TRAY_SCALE_SLIDER));
+  tri_view_->AddView(TriView::Container::CENTER, slider_);
+
+  set_background(views::Background::CreateThemedSolidBackground(
+      this, ui::NativeTheme::kColorId_BubbleBackground));
+
+  if (!is_default_view_) {
+    tri_view_->SetContainerVisible(TriView::Container::END, false);
+    Layout();
+    return;
+  }
+
+  more_button_ = new ButtonListenerActionableView(
+      owner_, TrayPopupInkDropStyle::INSET_BOUNDS, this);
+  TrayPopupUtils::ConfigureContainer(TriView::Container::END, more_button_);
+
+  more_button_->SetInkDropMode(views::InkDropHostView::InkDropMode::ON);
+  more_button_->SetBorder(
+      views::CreateEmptyBorder(gfx::Insets(0, kTrayPopupButtonEndMargin)));
+  tri_view_->AddView(TriView::Container::END, more_button_);
+
+  more_button_->AddChildView(TrayPopupUtils::CreateMoreImageView());
+  more_button_->SetAccessibleName(
+      l10n_util::GetStringUTF16(IDS_ASH_STATUS_TRAY_SCALE));
+  Layout();
+}
+
+ScaleView::~ScaleView() {}
+
+void ScaleView::ButtonPressed(views::Button* sender, const ui::Event& event) {
+  if (sender == more_button_)
+    owner_->TransitionDetailedView();
+}
+
+void ScaleView::SliderValueChanged(views::Slider* sender,
+                                   float value,
+                                   float old_value,
+                                   views::SliderChangeReason reason) {
+  if (reason == views::VALUE_CHANGED_BY_USER) {
+    label_->SetText(
+        base::UTF8ToUTF16(base::StringPrintf("%.2f", 1.f + value * 2.0f)));
+  }
+}
+
+void ScaleView::SliderDragEnded(views::Slider* sender) {
+  display::Display::SetForceDeviceScaleFactor(1.f + slider_->value() * 2.0f);
+  ash::Shell::Get()->display_manager()->UpdateDisplays();
+}
+
+}  // namespace tray
+}  // namespace ash