Add setting to isolate zoom changes by default.

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/chromecast_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
@@ skipping 423 matching lines @@
     "webui/version_handler.h",
     "webui/version_handler_chromeos.cc",
     "webui/version_handler_chromeos.h",
     "webui/version_ui.cc",
     "webui/version_ui.h",
     "window_sizer/window_sizer_mac.mm",
     "zoom/chrome_zoom_level_otr_delegate.cc",
     "zoom/chrome_zoom_level_otr_delegate.h",
     "zoom/chrome_zoom_level_prefs.cc",
     "zoom/chrome_zoom_level_prefs.h",
+    "zoom/chrome_zoom_prefs_helper.cc",
+    "zoom/chrome_zoom_prefs_helper.h",
   ]
 
   defines = []
   libs = []
 
   configs += [
     ":ui_warnings",
     "//build/config:precompiled_headers",
     "//build/config/compiler:wexit_time_destructors",
   ]
@@ skipping 3053 matching lines @@
       "test/test_confirm_bubble_model.cc",
       "test/test_confirm_bubble_model.h",
     ]
     deps += [ "//chrome/test:test_support_ui" ]
   }
 
   if (enable_extensions) {
     deps += [ "//extensions/browser" ]
   }
 }