Update horizontal tabs styling

browser/about_flags.cc

@@ -361,16 +361,24 @@
 #endif  // BUILDFLAG(IS_ANDROID)
 
 #if !BUILDFLAG(IS_ANDROID)
-#define BRAVE_SHARED_PINNED_TABS                                  \
-  EXPAND_FEATURE_ENTRIES({                                        \
-      "brave-shared-pinned-tabs",                                 \
-      "Shared pinned tab",                                        \
-      "Pinned tabs are shared across windows",                    \
-      kOsWin | kOsMac | kOsLinux,                                 \
-      FEATURE_VALUE_TYPE(tabs::features::kBraveSharedPinnedTabs), \
-  })
+#define BRAVE_TABS_FEATURE_ENTRIES                                        \
+  EXPAND_FEATURE_ENTRIES(                                                 \
+      {                                                                   \
+          "brave-shared-pinned-tabs",                                     \
+          "Shared pinned tab",                                            \
+          "Pinned tabs are shared across windows",                        \
+          kOsWin | kOsMac | kOsLinux,                                     \
+          FEATURE_VALUE_TYPE(tabs::features::kBraveSharedPinnedTabs),     \
+      },                                                                  \
+      {                                                                   \
+          "brave-horizontal-tabs-update",                                 \
+          "Updated horizontal tabs design",                               \
+          "Updates the look and feel or horizontal tabs",                 \
+          kOsWin | kOsMac | kOsLinux,                                     \
+          FEATURE_VALUE_TYPE(tabs::features::kBraveHorizontalTabsUpdate), \
+      })
 #else
-#define BRAVE_SHARED_PINNED_TABS
+#define BRAVE_TABS_FEATURE_ENTRIES
 #endif
 
 #if BUILDFLAG(ENABLE_AI_CHAT)
@@ -887,7 +895,7 @@
   BRAVE_BACKGROUND_VIDEO_PLAYBACK_ANDROID                                      \
   BRAVE_SAFE_BROWSING_ANDROID                                                  \
   BRAVE_CHANGE_ACTIVE_TAB_ON_SCROLL_EVENT_FEATURE_ENTRIES                      \
-  BRAVE_SHARED_PINNED_TABS                                                     \
+  BRAVE_TABS_FEATURE_ENTRIES                                                   \
   BRAVE_AI_CHAT                                                                \
   BRAVE_AI_CHAT_HISTORY                                                        \
   LAST_BRAVE_FEATURE_ENTRIES_ITEM  // Keep it as the last item.

browser/ui/brave_layout_constants.cc

@@ -5,9 +5,12 @@
 
 #include "brave/browser/ui/brave_layout_constants.h"
 
+#include "brave/browser/ui/tabs/features.h"
 #include "chrome/browser/ui/layout_constants.h"
 #include "ui/base/pointer/touch_ui_controller.h"
 
+using tabs::features::HorizontalTabsUpdateEnabled;
+
 // Returns a |nullopt| if the UI color is not handled by Brave.
 absl::optional<int> GetBraveLayoutConstant(LayoutConstant constant) {
   const bool touch = ui::TouchUiController::Get()->touch_ui();
@@ -18,7 +21,15 @@ absl::optional<int> GetBraveLayoutConstant(LayoutConstant constant) {
   //     ui::MaterialDesignController::IsNewerMaterialUi();
   switch (constant) {
     case TAB_HEIGHT: {
-      return (touch ? 41 : 30) + GetLayoutConstant(TABSTRIP_TOOLBAR_OVERLAP);
+      const int tab_height = HorizontalTabsUpdateEnabled() ? 36 : 30;
+      return (touch ? 41 : tab_height) +
+             GetLayoutConstant(TABSTRIP_TOOLBAR_OVERLAP);
+    }
+    case TABSTRIP_TOOLBAR_OVERLAP: {
+      if (!HorizontalTabsUpdateEnabled()) {
+        return absl::nullopt;
+      }
+      return 0;
     }
     case TAB_SEPARATOR_HEIGHT: {
       return 24;

browser/ui/color/brave_color_mixer.cc

@@ -185,6 +185,8 @@ void AddChromeLightThemeColorMixer(ui::ColorProvider* provider,
   mixer[kColorTabForegroundActiveFrameActive] = {kLightToolbarIcon};
   mixer[kColorTabForegroundInactiveFrameActive] = {
       kColorTabForegroundActiveFrameActive};
+  mixer[kColorTabStrokeFrameActive] = {SkColorSetA(SK_ColorBLACK, 0.07 * 255)};
+  mixer[kColorTabStrokeFrameInactive] = {kColorTabStrokeFrameActive};
   mixer[kColorToolbar] = {kLightToolbar};
   mixer[kColorToolbarButtonIcon] = {kColorTabForegroundActiveFrameActive};
   mixer[kColorToolbarButtonIconInactive] = {

browser/ui/tabs/BUILD.gn

@@ -12,12 +12,14 @@ source_set("tabs") {
 
   if (!is_android) {
     sources = [
+      "brave_tab_layout_constants.h",
       "brave_tab_menu_model.cc",
       "brave_tab_menu_model.h",
       "brave_tab_prefs.cc",
       "brave_tab_prefs.h",
       "brave_tab_strip_model.cc",
       "brave_tab_strip_model.h",
+      "brave_tab_style.h",
       "brave_vertical_tab_color_mixer.cc",
       "brave_vertical_tab_color_mixer.h",
       "features.cc",

browser/ui/tabs/brave_tab_layout_constants.h

@@ -0,0 +1,54 @@
+/* Copyright (c) 2023 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_BROWSER_UI_TABS_BRAVE_TAB_LAYOUT_CONSTANTS_H_
+#define BRAVE_BROWSER_UI_TABS_BRAVE_TAB_LAYOUT_CONSTANTS_H_
+
+namespace brave_tabs {
+
+// Horizontal tab layout:
+//
+// The upstream tab implemenation assumes that tab view bounds overlap. In order
+// to create a gap between tabs without violating these assumptions, tabs views
+// are given a small overlap. Rounded tab rectangles are drawn centered and
+// inset horizontally by an amount that will create the required visual gap.
+
+// The amount of space before the first tab.
+constexpr int kHorizontalTabStripLeftMargin = 8;
+
+// The amount of vertical spacing between the top and bottom of tabs and the
+// bounds of the tab strip region. The portion of this space below tabs will be
+// occupied by tab group underlines.
+constexpr int kHorizontalTabStripVerticalSpacing = 4;
+
+// The visual gap between tabs.
+constexpr int kHorizontalTabGap = 4;
+
+// The amount of overlap between tabs. Based on upstream assumptions, tab views
+// must have a non-negative overlap. Furthermore, tab separators will not render
+// correctly if the tab overlap is zero.
+constexpr int kHorizontalTabOverlap = 2;
+
+// The horizontal difference between the edge of the tab view and the visual
+// edge of the rendered tab.
+constexpr int kHorizontalTabInset =
+    (kHorizontalTabGap + kHorizontalTabOverlap) / 2;
+
+// The content padding within a tab.
+constexpr int kHorizontalTabPadding = 6;
+
+// The horizontal difference between the visual edge of a tab group and the
+// bounds of the group underline.
+constexpr int kHorizontalGroupUnderlineInset = 2;
+
+// The tab border radius.
+constexpr int kTabBorderRadius = 8;
+
+// The size of the group header slot when the title is empty.
+constexpr int kEmptyGroupTitleSize = 22;
+
+}  // namespace brave_tabs
+
+#endif  // BRAVE_BROWSER_UI_TABS_BRAVE_TAB_LAYOUT_CONSTANTS_H_

browser/ui/tabs/brave_tab_style.h

@@ -0,0 +1,57 @@
+/* Copyright (c) 2023 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_BROWSER_UI_TABS_BRAVE_TAB_STYLE_H_
+#define BRAVE_BROWSER_UI_TABS_BRAVE_TAB_STYLE_H_
+
+#include "brave/browser/ui/tabs/brave_tab_layout_constants.h"
+#include "brave/browser/ui/tabs/features.h"
+#include "chrome/browser/ui/layout_constants.h"
+#include "ui/gfx/geometry/insets.h"
+
+// A subclass of TabStyle used to customize tab layout and visuals. It is
+// implemented as a template because it must be included in the source file
+// override before the base class definition.
+template <typename TabStyleBase>
+class BraveTabStyle : public TabStyleBase {
+ public:
+  int GetTabOverlap() const override {
+    if (!tabs::features::HorizontalTabsUpdateEnabled()) {
+      return TabStyleBase::GetTabOverlap();
+    }
+    return brave_tabs::kHorizontalTabOverlap;
+  }
+
+  int GetTopCornerRadius() const override {
+    if (!tabs::features::HorizontalTabsUpdateEnabled()) {
+      return TabStyleBase::GetTopCornerRadius();
+    }
+    return brave_tabs::kTabBorderRadius;
+  }
+
+  int GetBottomCornerRadius() const override {
+    if (!tabs::features::HorizontalTabsUpdateEnabled()) {
+      return TabStyleBase::GetBottomCornerRadius();
+    }
+    return brave_tabs::kTabBorderRadius;
+  }
+
+  gfx::Insets GetContentsInsets() const override {
+    if (!tabs::features::HorizontalTabsUpdateEnabled()) {
+      return TabStyleBase::GetContentsInsets();
+    }
+    return gfx::Insets::VH(
+        0, brave_tabs::kHorizontalTabPadding + brave_tabs::kHorizontalTabInset);
+  }
+
+  int GetPinnedWidth() const override {
+    if (!tabs::features::HorizontalTabsUpdateEnabled()) {
+      return TabStyleBase::GetPinnedWidth();
+    }
+    return GetLayoutConstant(TAB_HEIGHT) + brave_tabs::kHorizontalTabInset * 2;
+  }
+};
+
+#endif  // BRAVE_BROWSER_UI_TABS_BRAVE_TAB_STYLE_H_

browser/ui/tabs/features.cc

@@ -17,4 +17,12 @@ BASE_FEATURE(kBraveSharedPinnedTabs,
              "BraveSharedPinnedTabs",
              base::FEATURE_DISABLED_BY_DEFAULT);
 
+BASE_FEATURE(kBraveHorizontalTabsUpdate,
+             "BraveHorizontalTabsUpdate",
+             base::FEATURE_DISABLED_BY_DEFAULT);
+
+bool HorizontalTabsUpdateEnabled() {
+  return base::FeatureList::IsEnabled(kBraveHorizontalTabsUpdate);
+}
+
 }  // namespace tabs::features

browser/ui/tabs/features.h

@@ -17,6 +17,10 @@ BASE_DECLARE_FEATURE(kBraveChangeActiveTabOnScrollEvent);
 
 BASE_DECLARE_FEATURE(kBraveSharedPinnedTabs);
 
+BASE_DECLARE_FEATURE(kBraveHorizontalTabsUpdate);
+
+bool HorizontalTabsUpdateEnabled();
+
 }  // namespace tabs::features
 
 #endif  // BRAVE_BROWSER_UI_TABS_FEATURES_H_

browser/ui/views/frame/brave_browser_non_client_frame_view_mac.mm

@@ -8,6 +8,7 @@
 #include "brave/browser/ui/views/frame/brave_browser_non_client_frame_view_mac.h"
 
 #include "brave/browser/ui/tabs/brave_tab_prefs.h"
+#include "brave/browser/ui/tabs/features.h"
 #include "brave/browser/ui/views/frame/brave_non_client_hit_test_helper.h"
 #include "brave/browser/ui/views/frame/brave_window_frame_graphic.h"
 #include "brave/browser/ui/views/tabs/vertical_tab_utils.h"
@@ -66,7 +67,13 @@
     return 30;
   }
 
-  return BrowserNonClientFrameViewMac::GetTopInset(restored);
+  if (!tabs::features::HorizontalTabsUpdateEnabled()) {
+    return BrowserNonClientFrameViewMac::GetTopInset(restored);
+  }
+
+  // The tab region view maintains its own padding, but insert a small gap to
+  // give a bit more room for the frame resize handle.
+  return 2;
 }
 
 bool BraveBrowserNonClientFrameViewMac::ShouldShowWindowTitleForVerticalTabs()

browser/ui/views/frame/vertical_tab_strip_region_view.cc

@@ -309,7 +309,7 @@ class VerticalTabNewTabButton : public BraveNewTabButton {
                        float scale,
                        bool extend_to_top) const override {
     auto contents_bounds = GetContentsBounds();
-    const float radius = tabs::kUnpinnedTabBorderRadius * scale;
+    const float radius = GetCornerRadius() * scale;
     SkPath path;
     const gfx::Rect path_rect(origin.x(), origin.y(),
                               contents_bounds.width() * scale,

browser/ui/views/tabs/brave_compound_tab_container.cc

@@ -138,6 +138,7 @@ void BraveCompoundTabContainer::SetScrollEnabled(bool enabled) {
 
   if (enabled) {
     scroll_view_ = AddChildView(std::make_unique<CustomScrollView>());
+    scroll_view_->SetBackgroundThemeColorId(kColorToolbar);
     auto* contents_view =
         scroll_view_->SetContents(std::make_unique<ContentsView>(this));
     contents_view->AddChildView(base::to_address(unpinned_tab_container_));

browser/ui/views/tabs/brave_new_tab_button.cc

@@ -6,19 +6,26 @@
 #include "brave/browser/ui/views/tabs/brave_new_tab_button.h"
 
 #include <algorithm>
-#include <memory>
 #include <utility>
 
-#include "brave/browser/ui/color/brave_color_id.h"
-#include "chrome/app/chrome_command_ids.h"
-#include "chrome/browser/ui/layout_constants.h"
+#include "brave/browser/ui/tabs/features.h"
+#include "brave/components/vector_icons/vector_icons.h"
 #include "chrome/browser/ui/views/tabs/new_tab_button.h"
 #include "chrome/browser/ui/views/tabs/tab_strip.h"
 #include "ui/gfx/geometry/skia_conversions.h"
+#include "ui/gfx/paint_vector_icon.h"
 #include "ui/gfx/scoped_canvas.h"
+#include "ui/views/view_class_properties.h"
+
+using tabs::features::HorizontalTabsUpdateEnabled;
 
 // static
-const gfx::Size BraveNewTabButton::kButtonSize{24, 24};
+gfx::Size BraveNewTabButton::GetButtonSize() {
+  if (!HorizontalTabsUpdateEnabled()) {
+    return {24, 24};
+  }
+  return {28, 28};
+}
 
 // static
 SkPath BraveNewTabButton::GetBorderPath(const gfx::Point& origin,
@@ -44,7 +51,7 @@ SkPath BraveNewTabButton::GetBorderPath(const gfx::Point& origin,
 
 gfx::Size BraveNewTabButton::CalculatePreferredSize() const {
   // Overriden so that we use Brave's custom button size
-  gfx::Size size = kButtonSize;
+  gfx::Size size = GetButtonSize();
   const auto insets = GetInsets();
   size.Enlarge(insets.width(), insets.height());
   return size;
@@ -59,12 +66,31 @@ SkPath BraveNewTabButton::GetBorderPath(const gfx::Point& origin,
 
 BraveNewTabButton::BraveNewTabButton(TabStrip* tab_strip,
                                      PressedCallback callback)
-    : NewTabButton(tab_strip, std::move(callback)) {}
+    : NewTabButton(tab_strip, std::move(callback)) {
+  if (HorizontalTabsUpdateEnabled()) {
+    // Ensure that the new tab button is vertically centered within its flex
+    // layout container.
+    SetProperty(views::kCrossAxisAlignmentKey, views::LayoutAlignment::kCenter);
+  }
+}
 
 BraveNewTabButton::~BraveNewTabButton() = default;
 
 void BraveNewTabButton::PaintIcon(gfx::Canvas* canvas) {
   gfx::ScopedCanvas scoped_canvas(canvas);
+
+  if (HorizontalTabsUpdateEnabled()) {
+    // Instead of letting `NewTabButton` draw a "plus", paint a vector icon to
+    // the canvas in the center of the view.
+    constexpr int kIconSize = 16;
+    gfx::Rect bounds = GetContentsBounds();
+    canvas->Translate(gfx::Vector2d((bounds.width() - kIconSize) / 2,
+                                    (bounds.height() - kIconSize) / 2));
+    gfx::PaintVectorIcon(canvas, kLeoPlusAddIcon, kIconSize,
+                         GetForegroundColor());
+    return;
+  }
+
   // Shim base implementation's painting
   // Overriden to fix chromium assumption that border radius
   // will be 50% of width.

browser/ui/views/tabs/brave_new_tab_button.h

@@ -21,15 +21,14 @@ class BraveNewTabButton : public NewTabButton {
   // These static members are shared with BraveTabSearchButton
   // TODO(sko) If we could make TabSearchButton inherit BraveNewTabButton,
   // we might not need these any more.
-  static const gfx::Size kButtonSize;
+  static gfx::Size GetButtonSize();
   static SkPath GetBorderPath(const gfx::Point& origin,
                               float scale,
                               bool extend_to_top,
                               int border_radius,
                               const gfx::Size& contents_bounds);
+
   BraveNewTabButton(TabStrip* tab_strip, PressedCallback callback);
-  BraveNewTabButton(const BraveNewTabButton&) = delete;
-  BraveNewTabButton& operator=(const BraveNewTabButton&) = delete;
   ~BraveNewTabButton() override;
 
  protected: