Use bigger toolbar new tab button for WebUI tab strip

Bug: 1032649
Change-Id: Ifc70677c15ad29dae8db64b98feb73bb6f901110
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1961069
Commit-Queue: Collin Baker <collinbaker@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#723615}

chrome/app/vector_icons/BUILD.gn

@@ -5,6 +5,7 @@
 import("//build/util/branding.gni")
 import("//components/vector_icons/vector_icons.gni")
 import("//device/vr/buildflags/buildflags.gni")
+import("//ui/webui/webui_features.gni")
 
 aggregate_vector_icons("chrome_vector_icons") {
   icon_directory = "."
@@ -214,6 +215,10 @@ aggregate_vector_icons("chrome_vector_icons") {
     icons += [ "open_in_browser.icon" ]
   }
 
+  if (enable_webui_tab_strip) {
+    icons += [ "new_tab_toolbar_button.icon" ]
+  }
+
   if (is_chrome_branded) {
     icons += [
       "google_chrome/google_g_logo.icon",

chrome/app/vector_icons/new_tab_toolbar_button.icon

+// Copyright 2019 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.
+
+// New tab button in toolbar used with the touch-friendly WebUI tab strip.
+
+CANVAS_DIMENSIONS, 24,
+MOVE_TO, 21, 13,
+R_H_LINE_TO, -8,
+R_V_LINE_TO, 8,
+R_H_LINE_TO, -3,
+R_V_LINE_TO, -8,
+H_LINE_TO, 2,
+R_V_LINE_TO, -3,
+R_H_LINE_TO, 8,
+V_LINE_TO, 2,
+R_H_LINE_TO, 3,
+R_V_LINE_TO, 8,
+R_H_LINE_TO, 8,
+CLOSE

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

@@ -209,8 +209,9 @@ void WebUITabStripContainerView::UpdateButtons() {
   const SkColor normal_color =
       GetThemeProvider()->GetColor(ThemeProperties::COLOR_TOOLBAR_BUTTON_ICON);
   if (new_tab_button_) {
-    new_tab_button_->SetImage(views::Button::STATE_NORMAL,
-                              gfx::CreateVectorIcon(kAddIcon, normal_color));
+    new_tab_button_->SetImage(
+        views::Button::STATE_NORMAL,
+        gfx::CreateVectorIcon(kNewTabToolbarButtonIcon, normal_color));
   }
 }