Add setting to isolate zoom changes by default.

chrome/common/pref_names.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/common/pref_names.h"
 
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "chrome/common/features.h"
 #include "chrome/common/pref_font_webkit_names.h"
@@ skipping 1079 matching lines @@
     "profile.content_settings.plugin_whitelist";
 #endif
 
 // Double that indicates the default zoom level.
 const char kPartitionDefaultZoomLevel[] = "partition.default_zoom_level";
 
 // Dictionary that maps hostnames to zoom levels.  Hosts not in this pref will
 // be displayed at the default zoom level.
 const char kPartitionPerHostZoomLevels[] = "partition.per_host_zoom_levels";
 
+// Whether zoom changes should be scoped to origins by default.
+// If false, zoom changes are per-tab.
+const char kPartitionZoomScopeIsPerOrigin[] =

[Kevin McNee, 2017/02/03 23:17:20]

Shall we get UMA data about the usage of this option?

[wjmaclean, 2017/02/06 16:09:07]

Definitely!

+    "partition.zoom_scope_is_per_origin";
+
 #if !defined(OS_ANDROID)
 const char kPinnedTabs[] = "pinned_tabs";
 #endif
 
 // Preference to disable 3D APIs (WebGL, Pepper 3D).
 const char kDisable3DAPIs[] = "disable_3d_apis";
 
 const char kEnableDeprecatedWebPlatformFeatures[] =
     "enable_deprecated_web_platform_features";
 
@@ skipping 1272 matching lines @@
 // default search engine, if it is the Google search engine.
 const char kGoogleDSEGeolocationSetting[] = "google_dse_geolocation_setting";
 
 // A dictionary of manifest URLs of Web Share Targets to a dictionary containing
 // attributes of its share_target field found in its manifest. Each key in the
 // dictionary is the name of the attribute, and the value is the corresponding
 // value.
 const char kWebShareVisitedTargets[] = "profile.web_share.visited_targets";
 
 }  // namespace prefs