mus: Use the new drag API to implement tab dragging in chrome.

chrome/browser/ui/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
 
 gypi_values = exec_script("//build/gypi_to_gn.py",
@@ skipping 312 matching lines @@
     if (!is_mac) {
       sources +=
           rebase_path(gypi_values.chrome_browser_ui_views_non_mac_sources,
                       ".",
                       "//chrome")
       if (use_aura) {
         deps += [
           "//components/mus/public/cpp",
           "//components/mus/public/interfaces",
         ]
+
+        # TODO(erg): These files hard depend on mus, and thus can't be in a gyp
+        # build. When gyp goes away, merge this back into the sources list.
+        sources += [
+          "views/tabs/window_finder_mus.cc",
+          "views/tabs/window_finder_mus.h",
+        ]
       }
       if (enable_extensions) {
         sources += rebase_path(
                 gypi_values.chrome_browser_ui_views_extensions_non_mac_sources,
                 ".",
                 "//chrome")
       }
     }
     if (use_ash) {
       sources += rebase_path(gypi_values.chrome_browser_ui_ash_views_sources,
@@ skipping 372 matching lines @@
     "//chrome/browser",
     "//content/public/browser",
     "//content/public/common",
     "//content/test:test_support",
     "//net:test_support",
     "//skia",
     "//testing/gtest",
     "//ui/base",
   ]
 }