Add setting to isolate zoom changes by default.

chrome/browser/ui/zoom/chrome_zoom_prefs_helper.cc

Index: chrome/browser/ui/zoom/chrome_zoom_prefs_helper.cc
diff --git a/chrome/browser/ui/zoom/chrome_zoom_prefs_helper.cc b/chrome/browser/ui/zoom/chrome_zoom_prefs_helper.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4676b0d1b29c519738c084563f92c926f9ba2fe0
--- /dev/null
+++ b/chrome/browser/ui/zoom/chrome_zoom_prefs_helper.cc
@@ -0,0 +1,90 @@
+// Copyright 2017 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_prefs_helper.h"
+
+#include "base/files/file_path.h"
+#include "base/memory/ptr_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/values.h"
+#include "components/prefs/pref_service.h"
+
+namespace {
+
+std::string GetHash(const base::FilePath& relative_path) {
+  size_t int_key = BASE_HASH_NAMESPACE::hash<base::FilePath>()(relative_path);
+  return base::SizeTToString(int_key);
+}
+
+}  // namespace
+
+ChromeZoomPrefsHelper::ChromeZoomPrefsHelper(
+    PrefService* pref_service,
+    const base::FilePath& profile_path,
+    const base::FilePath& partition_path)
+    : pref_service_(pref_service) {
+  DCHECK(pref_service_);
+
+  DCHECK(!partition_path.empty());
+  DCHECK((partition_path == profile_path) ||
+         profile_path.IsParent(partition_path));
+  // Create a partition_key string with no '.'s in it. For the default
+  // StoragePartition, this string will always be "0".
+  base::FilePath partition_relative_path;
+  profile_path.AppendRelativePath(partition_path, &partition_relative_path);
+  partition_key_ = GetHash(partition_relative_path);
+}
+
+std::string ChromeZoomPrefsHelper::GetHashForTesting(
+    const base::FilePath& relative_path) {
+  return GetHash(relative_path);
+}
+
+bool ChromeZoomPrefsHelper::GetBoolean(const char* pref_name,
+                                       bool* value) const {
+  return pref_service_->GetDictionary(pref_name)->GetBoolean(partition_key_,
+                                                             value);
+}
+
+void ChromeZoomPrefsHelper::SetBoolean(const char* pref_name, bool value) {
+  DictionaryPrefUpdate update(pref_service_, pref_name);
+  update->SetBoolean(partition_key_, value);
+}
+
+bool ChromeZoomPrefsHelper::GetDouble(const char* pref_name,
+                                      double* value) const {
+  return pref_service_->GetDictionary(pref_name)->GetDouble(partition_key_,
+                                                            value);
+}
+
+void ChromeZoomPrefsHelper::SetDouble(const char* pref_name, double value) {
+  DictionaryPrefUpdate update(pref_service_, pref_name);
+  update->SetDouble(partition_key_, value);
+}
+
+bool ChromeZoomPrefsHelper::GetDictionary(
+    const char* pref_name,
+    const base::DictionaryValue** value) const {
+  return pref_service_->GetDictionary(pref_name)->GetDictionary(partition_key_,
+                                                                value);
+}
+
+std::unique_ptr<DictionaryPrefUpdate> ChromeZoomPrefsHelper::GetUpdate(
+    const char* pref_name) {
+  return base::MakeUnique<DictionaryPrefUpdate>(pref_service_, pref_name);
+}
+
+base::DictionaryValue* ChromeZoomPrefsHelper::GetMutableDictionary(
+    DictionaryPrefUpdate* update) const {
+  base::DictionaryValue* dictionaries = update->Get();
+  DCHECK(dictionaries);
+
+  base::DictionaryValue* dictionary = nullptr;
+  if (!dictionaries->GetDictionary(partition_key_, &dictionary)) {
+    dictionary = new base::DictionaryValue();
+    dictionaries->Set(partition_key_, base::WrapUnique(dictionary));
+  }
+
+  return dictionary;
+}