Add setting to isolate zoom changes by default.

chrome/browser/ui/zoom/chrome_zoom_level_prefs.cc

 // 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.
 
 #include "chrome/browser/ui/zoom/chrome_zoom_level_prefs.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 72 matching lines @@
   default_zoom_level_dictionary->GetDouble(partition_key_, &default_zoom_level);
   return default_zoom_level;
 }
 
 std::unique_ptr<ChromeZoomLevelPrefs::DefaultZoomLevelSubscription>
 ChromeZoomLevelPrefs::RegisterDefaultZoomLevelCallback(
     const base::Closure& callback) {
   return default_zoom_changed_callbacks_.Add(callback);
 }
 
+void ChromeZoomLevelPrefs::SetIsOriginScopePref(bool default_per_origin) {
+  if (default_per_origin == GetIsOriginScopePref())
+    return;
+
+  DictionaryPrefUpdate update(
+      pref_service_, prefs::kPartitionDefaultZoomOriginScope);
+  update->SetBoolean(partition_key_, default_per_origin);
+  default_scope_changed_callbacks_.Notify();
+}
+
+bool ChromeZoomLevelPrefs::GetIsOriginScopePref() const {
+  bool default_per_origin = true;

[wjmaclean, 2017/01/19 21:09:05]

Rename |default_per_origin| to something like |is_per_origin| to make it clear
we're not (always) using a default value here?

[Kevin McNee, 2017/02/03 22:51:34]

Done.

+
+  const base::DictionaryValue* default_zoom_origin_scope_dictionary =
+      pref_service_->GetDictionary(prefs::kPartitionDefaultZoomOriginScope);
+  // If no value has been previously set, |default_per_origin| will be untouched
+  // from the default value we've set above.
+  default_zoom_origin_scope_dictionary->GetBoolean(partition_key_,
+                                                   &default_per_origin);
+  return default_per_origin;
+}
+
+std::unique_ptr<ChromeZoomLevelPrefs::DefaultZoomScopeSubscription>
+ChromeZoomLevelPrefs::RegisterDefaultZoomScopeCallback(
+    const base::Closure& callback) {
+  return default_scope_changed_callbacks_.Add(callback);
+}
+
 void ChromeZoomLevelPrefs::OnZoomLevelChanged(
     const content::HostZoomMap::ZoomLevelChange& change) {
   // If there's a manager to aggregate ZoomLevelChanged events, pass this event
   // along. Since we already hold a subscription to our associated HostZoomMap,
   // we don't need to create a separate subscription for this.
   if (zoom_event_manager_)
     zoom_event_manager_->OnZoomLevelChanged(change);
 
   if (change.mode != content::HostZoomMap::ZOOM_CHANGED_FOR_HOST)
     return;
@@ skipping 93 matching lines @@
                                             &host_zoom_dictionary)) {
     // Since we're calling this before setting up zoom_subscription_ below we
     // don't need to worry that host_zoom_dictionary is indirectly affected
     // by calls to HostZoomMap::SetZoomLevelForHost().
     ExtractPerHostZoomLevels(host_zoom_dictionary,
                              true /* sanitize_partition_host_zoom_levels */);
   }
   zoom_subscription_ = host_zoom_map_->AddZoomLevelChangedCallback(base::Bind(
       &ChromeZoomLevelPrefs::OnZoomLevelChanged, base::Unretained(this)));
 }