Implements a display scale tray setting behind a chrome switch

chrome/browser/about_flags.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/about_flags.h"
 
 #include <iterator>
 #include <map>
 #include <set>
 #include <utility>
@@ skipping 2826 matching lines @@
 
     {"use-suggestions-even-if-few",
      flag_descriptions::kUseSuggestionsEvenIfFewFeatureName,
      flag_descriptions::kUseSuggestionsEvenIfFewFeatureDescription, kOsAll,
      FEATURE_VALUE_TYPE(suggestions::kUseSuggestionsEvenIfFewFeature)},
 
     {"enable-location-hard-reload", flag_descriptions::kLocationHardReloadName,
      flag_descriptions::kLocationHardReloadDescription, kOsAll,
      FEATURE_VALUE_TYPE(features::kLocationHardReload)},
 
+#if defined(USE_ASH) && defined(OS_CHROMEOS)
+    {"ash-enable-scale-settings-tray",
+     flag_descriptions::kAshEnableScaleSettingsTrayName,
+     flag_descriptions::kAshEnableScaleSettingsTrayDescription, kOsCrOS,
+     SINGLE_VALUE_TYPE(ash::switches::kAshEnableScaleSettingsTray)},
+#endif

[oshima, 2017/05/06 19:50:22]

I prefer not to expose this to users.
Rather we should hook up with the UI scale.

+
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms/enums.xml. See note in
     // enums.xml and don't forget to run AboutFlagsHistogramTest unit test.
 };
 
 class FlagsStateSingleton {
  public:
   FlagsStateSingleton()
       : flags_state_(kFeatureEntries, arraysize(kFeatureEntries)) {}
   ~FlagsStateSingleton() {}
@@ skipping 205 matching lines @@
 const base::HistogramBase::Sample kBadSwitchFormatHistogramId = 0;
 
 const FeatureEntry* GetFeatureEntries(size_t* count) {
   *count = arraysize(kFeatureEntries);
   return kFeatureEntries;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags