Improvements to support scrollable tabstrip.

Creates a mode that allows scrolling without a scrollbar in either
direction as well as the ability to treat scroll-specific events (e.g.
mousewheel events) as horizontal scroll inputs.

Changes:
* Adds a third scrollbar state: visible but not enabled
* Allows enabled/disabled/invisible state for vertical scrollbar as well
as horizontal (previously only horizontal scrollbar could be hidden/
disabled).
* Adds the option to treat vertical scroll events as horizontal, so that
for example a mousewheel or vertical scroll gesture can allow a
horizontal-scroll-only pane to scroll.

Bug: 1122214
Change-Id: I7f01b26b33ede76e1903ee37a493a2818b7b1103
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2433254
Commit-Queue: Dana Fried <dfried@chromium.org>
Reviewed-by: Robert Liao <robliao@chromium.org>
Reviewed-by: Charlene Yan <cyan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813839}

chrome/browser/ui/views/autofill/autofill_popup_view_native_views.cc

@@ -1163,7 +1163,8 @@ void AutofillPopupViewNativeViews::CreateChildViews() {
     }
 
     scroll_view_ = new views::ScrollView();
-    scroll_view_->SetHideHorizontalScrollBar(true);
+    scroll_view_->SetHorizontalScrollBarMode(
+        views::ScrollView::ScrollBarMode::kDisabled);
     body_container_ = scroll_view_->SetContents(std::move(body_container));
     scroll_view_->SetDrawOverflowIndicator(false);
     scroll_view_->ClipHeightTo(0, body_container_->GetPreferredSize().height());

chrome/browser/ui/views/autofill/payments/local_card_migration_dialog_view.cc

@@ -160,7 +160,8 @@ std::unique_ptr<views::ScrollView> CreateCardList(
   }
 
   auto card_list_scroll_view = std::make_unique<views::ScrollView>();
-  card_list_scroll_view->SetHideHorizontalScrollBar(true);
+  card_list_scroll_view->SetHorizontalScrollBarMode(
+      views::ScrollView::ScrollBarMode::kDisabled);
   card_list_scroll_view->SetContents(std::move(card_list_view));
   card_list_scroll_view->SetDrawOverflowIndicator(false);
   constexpr int kCardListScrollViewHeight = 140;

chrome/browser/ui/views/desktop_capture/desktop_media_picker_views.cc

@@ -126,7 +126,8 @@ DesktopMediaPickerDialogView::DesktopMediaPickerDialogView(
         screen_scroll_view->ClipHeightTo(
             kGenericScreenStyle.item_size.height(),
             kGenericScreenStyle.item_size.height() * 2);
-        screen_scroll_view->SetHideHorizontalScrollBar(true);
+        screen_scroll_view->SetHorizontalScrollBarMode(
+            views::ScrollView::ScrollBarMode::kDisabled);
 
         panes.push_back(
             std::make_pair(screen_title_text, std::move(screen_scroll_view)));
@@ -156,7 +157,8 @@ DesktopMediaPickerDialogView::DesktopMediaPickerDialogView(
 
         window_scroll_view->ClipHeightTo(kWindowStyle.item_size.height(),
                                          kWindowStyle.item_size.height() * 2);
-        window_scroll_view->SetHideHorizontalScrollBar(true);
+        window_scroll_view->SetHorizontalScrollBarMode(
+            views::ScrollView::ScrollBarMode::kDisabled);
 
         panes.push_back(
             std::make_pair(window_title_text, std::move(window_scroll_view)));

chrome/browser/ui/views/extensions/extension_install_blocked_dialog_view.cc

@@ -121,7 +121,8 @@ void ExtensionInstallBlockedDialogView::AddCustomMessageContents(
   header_label->SizeToFit(content_width);
 
   auto* scroll_view = AddChildView(std::make_unique<views::ScrollView>());
-  scroll_view->SetHideHorizontalScrollBar(true);
+  scroll_view->SetHorizontalScrollBarMode(
+      views::ScrollView::ScrollBarMode::kDisabled);
   scroll_view->SetContents(std::move(extension_info_container));
   scroll_view->ClipHeightTo(
       0, provider->GetDistanceMetric(

chrome/browser/ui/views/extensions/extension_install_dialog_view.cc

@@ -520,7 +520,8 @@ void ExtensionInstallDialogView::CreateContents() {
   }
 
   scroll_view_ = new views::ScrollView();
-  scroll_view_->SetHideHorizontalScrollBar(true);
+  scroll_view_->SetHorizontalScrollBarMode(
+      views::ScrollView::ScrollBarMode::kDisabled);
   scroll_view_->SetContents(std::move(extension_info_container));
   scroll_view_->ClipHeightTo(
       0, provider->GetDistanceMetric(

chrome/browser/ui/views/extensions/extensions_menu_view.cc

@@ -132,7 +132,8 @@ void ExtensionsMenuView::Populate() {
   auto scroll_view = std::make_unique<views::ScrollView>();
   scroll_view->ClipHeightTo(0, kMaxExtensionButtonsHeightDp);
   scroll_view->SetDrawOverflowIndicator(false);
-  scroll_view->SetHideHorizontalScrollBar(true);
+  scroll_view->SetHorizontalScrollBarMode(
+      views::ScrollView::ScrollBarMode::kDisabled);
   scroll_view->SetContents(std::move(extension_buttons));
   AddChildView(std::move(scroll_view));
 

chrome/browser/ui/views/frame/browser_root_view.cc

@@ -17,6 +17,7 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser_commands.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
+#include "chrome/browser/ui/ui_features.h"
 #include "chrome/browser/ui/views/frame/browser_frame.h"
 #include "chrome/browser/ui/views/tabs/tab_strip.h"
 #include "chrome/browser/ui/views/tabs/tab_strip_controller.h"
@@ -259,7 +260,13 @@ const char* BrowserRootView::GetClassName() const {
 }
 
 bool BrowserRootView::OnMouseWheel(const ui::MouseWheelEvent& event) {
-  if (browser_defaults::kScrollEventChangesTab) {
+  // TODO(dfried): See if it's possible to move this logic deeper into the view
+  // hierarchy - ideally to TabStripRegionView.
+
+  // Scroll-event-changes-tab is incompatible with scrolling tabstrip, so
+  // disable it if the latter feature is enabled.
+  if (browser_defaults::kScrollEventChangesTab &&
+      !base::FeatureList::IsEnabled(features::kScrollableTabStrip)) {
     // Switch to the left/right tab if the wheel-scroll happens over the
     // tabstrip, or the empty space beside the tabstrip.
     views::View* hit_view = GetEventHandlerForPoint(event.location());

chrome/browser/ui/views/frame/tab_strip_region_view.cc

@@ -31,7 +31,8 @@ TabStripRegionView::TabStripRegionView(std::unique_ptr<TabStrip> tab_strip) {
         AddChildView(std::make_unique<views::ScrollView>(
             views::ScrollView::ScrollWithLayers::kEnabled));
     tab_strip_scroll_container->SetBackgroundColor(base::nullopt);
-    tab_strip_scroll_container->SetHideHorizontalScrollBar(true);
+    tab_strip_scroll_container->SetHorizontalScrollBarMode(
+        views::ScrollView::ScrollBarMode::kDisabled);
     tab_strip_container_ = tab_strip_scroll_container;
     tab_strip_scroll_container->SetContents(std::move(tab_strip));
   } else {

chrome/browser/ui/views/payments/payment_request_sheet_controller.cc

@@ -253,7 +253,8 @@ std::unique_ptr<views::View> PaymentRequestSheetController::CreateView() {
   scroll_ = layout->AddView(DisplayDynamicBorderForHiddenContents()
                                 ? std::make_unique<BorderedScrollView>()
                                 : std::make_unique<views::ScrollView>());
-  scroll_->SetHideHorizontalScrollBar(true);
+  scroll_->SetHorizontalScrollBarMode(
+      views::ScrollView::ScrollBarMode::kDisabled);
   pane_ = scroll_->SetContents(std::make_unique<views::View>());
   views::GridLayout* pane_layout =
       pane_->SetLayoutManager(std::make_unique<views::GridLayout>());

chrome/browser/ui/views/profiles/profile_menu_view_base.cc

@@ -913,7 +913,8 @@ void ProfileMenuViewBase::Reset() {
 
   // Create a scroll view to hold the components.
   auto scroll_view = std::make_unique<views::ScrollView>();
-  scroll_view->SetHideHorizontalScrollBar(true);
+  scroll_view->SetHorizontalScrollBarMode(
+      views::ScrollView::ScrollBarMode::kDisabled);
   // TODO(https://crbug.com/871762): it's a workaround for the crash.
   scroll_view->SetDrawOverflowIndicator(false);
   scroll_view->ClipHeightTo(0, GetMaxHeight());

chrome/browser/ui/views/supervised_user/parent_permission_dialog_view.cc

@@ -460,7 +460,8 @@ void ParentPermissionDialogView::CreateContents() {
 
     // Add section container to an enclosing scroll view.
     auto scroll_view = std::make_unique<views::ScrollView>();
-    scroll_view->SetHideHorizontalScrollBar(true);
+    scroll_view->SetHorizontalScrollBarMode(
+        views::ScrollView::ScrollBarMode::kDisabled);
     scroll_view->SetContents(std::move(install_permissions_section_container));
     scroll_view->ClipHeightTo(
         0, provider->GetDistanceMetric(

ui/views/controls/scroll_view.h

@@ -50,6 +50,19 @@ class VIEWS_EXPORT ScrollView : public View, public ScrollBarController {
   // Indicates whether or not scroll view is initialized with layer-scrolling.
   enum class ScrollWithLayers { kDisabled, kEnabled };
 
+  // Controls how a scroll bar appears and functions.
+  enum class ScrollBarMode {
+    // The scrollbar is hidden, and the pane will not respond to e.g. mousewheel
+    // events even if the contents are larger than the viewport.
+    kDisabled,
+    // The scrollbar is hidden whether or not the contents are larger than the
+    // viewport, but the pane will respond to scroll events.
+    kHiddenButEnabled,
+    // The scrollbar will be visible if the contents are larger than the
+    // viewport and the pane will respond to scroll events.
+    kEnabled
+  };
+
   ScrollView();
 
   // Additional constructor for overriding scrolling as defined by
@@ -110,8 +123,19 @@ class VIEWS_EXPORT ScrollView : public View, public ScrollBarController {
 
   bool GetUseColorId() const { return !!background_color_id_; }
 
-  bool GetHideHorizontalScrollBar() const { return hide_horizontal_scrollbar_; }
-  void SetHideHorizontalScrollBar(bool visible);
+  ScrollBarMode GetHorizontalScrollBarMode() const {
+    return horizontal_scroll_bar_mode_;
+  }
+  ScrollBarMode GetVerticalScrollBarMode() const {
+    return vertical_scroll_bar_mode_;
+  }
+  bool GetTreatAllScrollEventsAsHorizontal() const {
+    return treat_all_scroll_events_as_horizontal_;
+  }
+  void SetHorizontalScrollBarMode(ScrollBarMode horizontal_scroll_bar_mode);
+  void SetVerticalScrollBarMode(ScrollBarMode vertical_scroll_bar_mode);
+  void SetTreatAllScrollEventsAsHorizontal(
+      bool treat_all_scroll_events_as_horizontal);
 
   bool GetDrawOverflowIndicator() const { return draw_overflow_indicator_; }
   void SetDrawOverflowIndicator(bool draw_overflow_indicator);
@@ -165,6 +189,9 @@ class VIEWS_EXPORT ScrollView : public View, public ScrollBarController {
 
   class Viewport;
 
+  bool IsHorizontalScrollEnabled() const;
+  bool IsVerticalScrollEnabled() const;
+
   // Forces |contents_viewport_| to have a Layer (assuming it doesn't already).
   void EnableViewportLayer();
 
@@ -269,9 +296,14 @@ class VIEWS_EXPORT ScrollView : public View, public ScrollBarController {
   base::Optional<ui::NativeTheme::ColorId> background_color_id_ =
       ui::NativeTheme::kColorId_DialogBackground;
 
-  // If true, never show the horizontal scrollbar (even if the contents is wider
-  // than the viewport).
-  bool hide_horizontal_scrollbar_ = false;
+  // How to handle the case when the contents overflow the viewport.
+  ScrollBarMode horizontal_scroll_bar_mode_ = ScrollBarMode::kEnabled;
+  ScrollBarMode vertical_scroll_bar_mode_ = ScrollBarMode::kEnabled;
+
+  // Causes vertical scroll events (e.g. scrolling with the mousewheel) as
+  // horizontal events, to make scrolling in horizontal-only scroll situations
+  // easier for the user.
+  bool treat_all_scroll_events_as_horizontal_ = false;
 
   // In Harmony, the indicator is a focus ring. Pre-Harmony, the indicator is a
   // different border painter.
@@ -298,7 +330,9 @@ VIEW_BUILDER_VIEW_TYPE_PROPERTY(View, Contents)
 VIEW_BUILDER_VIEW_TYPE_PROPERTY(View, Header)
 VIEW_BUILDER_PROPERTY(base::Optional<ui::NativeTheme::ColorId>,
                       BackgroundThemeColorId)
-VIEW_BUILDER_PROPERTY(bool, HideHorizontalScrollBar)
+VIEW_BUILDER_PROPERTY(ScrollView::ScrollBarMode, HorizontalScrollBarMode)
+VIEW_BUILDER_PROPERTY(ScrollView::ScrollBarMode, VerticalScrollBarMode)
+VIEW_BUILDER_PROPERTY(bool, TreatAllScrollEventsAsHorizontal)
 VIEW_BUILDER_PROPERTY(bool, DrawOverflowIndicator)
 VIEW_BUILDER_PROPERTY(base::Optional<SkColor>, BackgroundColor)
 VIEW_BUILDER_VIEW_PROPERTY(ScrollBar, HorizontalScrollBar)

ui/views/metadata/type_conversion.cc

@@ -14,6 +14,7 @@
 #include "ui/base/ime/text_input_type.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/native_theme/native_theme.h"
+#include "ui/views/controls/scroll_view.h"
 
 namespace views {
 namespace metadata {
@@ -354,6 +355,14 @@ DEFINE_ENUM_CONVERTERS(ui::MenuSeparatorType,
                        {ui::MenuSeparatorType::PADDED_SEPARATOR,
                         base::ASCIIToUTF16("PADDED_SEPARATOR")})
 
+DEFINE_ENUM_CONVERTERS(views::ScrollView::ScrollBarMode,
+                       {views::ScrollView::ScrollBarMode::kDisabled,
+                        base::ASCIIToUTF16("kDisabled")},
+                       {views::ScrollView::ScrollBarMode::kHiddenButEnabled,
+                        base::ASCIIToUTF16("kHiddenButEnabled")},
+                       {views::ScrollView::ScrollBarMode::kEnabled,
+                        base::ASCIIToUTF16("kEnabled")})
+
 #define OP(enum_name) \
   { ui::NativeTheme::enum_name, base::ASCIIToUTF16(#enum_name) }
 DEFINE_ENUM_CONVERTERS(ui::NativeTheme::ColorId, NATIVE_THEME_COLOR_IDS)