Don't compile code for desktop zoom or GuestViews on mobile platforms.

chrome/browser/ui/prefs/prefs_tab_helper.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/ui/prefs/prefs_tab_helper.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <set>
 #include <string>
 
 #include "base/command_line.h"
 #include "base/macros.h"
 #include "base/memory/singleton.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/profiles/incognito_helpers.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/renderer_preferences_util.h"
-#include "chrome/browser/ui/zoom/chrome_zoom_level_prefs.h"
 #include "chrome/common/pref_font_webkit_names.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/pref_names_util.h"
 #include "chrome/grit/locale_settings.h"
 #include "chrome/grit/platform_locale_settings.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/overlay_user_pref_store.h"
@@ skipping 15 matching lines @@
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
 #include "chrome/browser/themes/theme_service.h"
 #include "chrome/browser/themes/theme_service_factory.h"
 #endif
 
 #if defined(OS_WIN)
 #include "base/win/windows_version.h"
 #endif
 
+#if !defined(OS_ANDROID)

[Bernhard Bauer, 2017/05/15 09:33:28]

Can you move this up before OS_POSIX etc. so the blocks are approximately
alphabetical?

[Kevin McNee, 2017/05/15 20:02:10]

Done.

+#include "chrome/browser/ui/zoom/chrome_zoom_level_prefs.h"
+#endif
+
 using content::WebContents;
 using content::WebPreferences;
 
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(PrefsTabHelper);
 
 namespace {
 
 // The list of prefs we want to observe.
 const char* const kPrefsToObserve[] = {
 #if BUILDFLAG(ENABLE_EXTENSIONS)
@@ skipping 393 matching lines @@
 PrefWatcher* PrefWatcher::Get(Profile* profile) {
   return PrefWatcherFactory::GetForProfile(profile);
 }
 
 PrefsTabHelper::PrefsTabHelper(WebContents* contents)
     : web_contents_(contents),
       profile_(Profile::FromBrowserContext(web_contents_->GetBrowserContext())),
       weak_ptr_factory_(this) {
   PrefService* prefs = profile_->GetPrefs();
   if (prefs) {
+#if !defined(OS_ANDROID)
     // If the tab is in an incognito profile, we track changes in the default
     // zoom level of the parent profile instead.
     Profile* profile_to_track = profile_->GetOriginalProfile();
     ChromeZoomLevelPrefs* zoom_level_prefs =
         profile_to_track->GetZoomLevelPrefs();
+#endif  // !defined(OS_ANDROID)
 
     base::Closure renderer_callback = base::Bind(

[msw, 2017/05/12 18:06:32]

It seems like you can include this in a !defined(OS_ANDROID) block, and merge
the two blocks above and below.

[Kevin McNee, 2017/05/15 20:02:10]

Done.

         &PrefsTabHelper::UpdateRendererPreferences, base::Unretained(this));
+#if !defined(OS_ANDROID)
     // Tests should not need to create a ZoomLevelPrefs.
     if (zoom_level_prefs) {
       default_zoom_level_subscription_ =
           zoom_level_prefs->RegisterDefaultZoomLevelCallback(renderer_callback);
     }
+#endif  // !defined(OS_ANDROID)
 
     PrefWatcher::Get(profile_)->RegisterHelper(this);
   }
 
   content::RendererPreferences* render_prefs =
       web_contents_->GetMutableRendererPrefs();
   renderer_preferences_util::UpdateFromSystemSettings(render_prefs,
                                                       profile_,
                                                       web_contents_);
 
@@ skipping 182 matching lines @@
 }
 
 void PrefsTabHelper::NotifyWebkitPreferencesChanged(
     const std::string& pref_name) {
 #if !defined(OS_ANDROID)
   OnFontFamilyPrefChanged(pref_name);
 #endif
 
   web_contents_->GetRenderViewHost()->OnWebkitPreferencesChanged();
 }