Port custom_tabs_client from GYP to GN

BUILD.gn

 # Copyright (c) 2013 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.
 
 # This is the root build file for GN. GN will start processing by loading this
 # file, and recursively load all dependencies until all dependencies are either
 # resolved or known not to exist (which will cause the build to fail). So if
 # you add a new build file, there must be some path of dependencies from this
 # file to your new one or GN won't know about it.
 
@@ skipping 201 matching lines @@
   if (is_win) {
     deps += [ "//chrome/tools/build/win/syzygy:chrome_dll_syzygy" ]
   }
 
   if (is_android) {
     if (!is_chromecast) {
       deps += [
         "//chrome/android:chrome_public_apk",
         "//chrome/android:chrome_public_test_apk",
         "//chrome/test/chromedriver/test/webview_shell:chromedriver_webview_shell_apk",
+        "//third_party/custom_tabs_client:custom_tabs_client_example_apk",
       ]
     }
 
     deps += [
       "//base/android/linker:chromium_android_linker",
       "//build/android/gyp/test:hello_world",
       "//build/android/rezip",
       "//third_party/errorprone:chromium_errorprone",
       "//tools/android:android_tools",
       "//tools/imagediff($host_toolchain)",
@@ skipping 751 matching lines @@
       if (target_cpu == "x86") {
         deps += [
           # "//content/shell:crash_service_win64", TODO(GYP): crbug.com/537009
         ]
       }
     } else {
       deps += [ "//breakpad:minidump_stackwalk" ]
     }
   }
 }