[protector] Support for collapsing multiple changes into a single one.

chrome/browser/protector/base_setting_change.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/protector/base_setting_change.h"
+#include "chrome/browser/protector/composite_settings_change.h"
 
 #include "base/logging.h"
 
 namespace protector {
 
+// static
+const size_t kDefaultSearchProviderChangeNamePriority = 100U;
+// static
+const size_t kSessionStartupChangeNamePriority = 50U;
+
+// static
+const size_t BaseSettingChange::kDefaultNamePriority = 0U;
+
 BaseSettingChange::BaseSettingChange()
     : profile_(NULL) {
 }
 
 BaseSettingChange::~BaseSettingChange() {
 }
 
+CompositeSettingsChange* BaseSettingChange::MergeWith(
+    BaseSettingChange* other) {
+  CompositeSettingsChange* composite_change = new CompositeSettingsChange();
+  CHECK(composite_change->Init(profile_));
+  composite_change->MergeWith(this);
+  composite_change->MergeWith(other);
+  return composite_change;
+}
+
+bool BaseSettingChange::Contains(const BaseSettingChange* other) const {
+  // BaseSettingChange can only contain itself.
+  return this == other;
+}
+
 bool BaseSettingChange::Init(Profile* profile) {
   DCHECK(profile);
   profile_ = profile;
   return true;
 }
 
 void BaseSettingChange::Apply(Browser* browser) {
 }
 
 void BaseSettingChange::Discard(Browser* browser) {
 }
 
 void BaseSettingChange::Timeout() {
 }
 
+BaseSettingChange::DisplayName BaseSettingChange::GetApplyDisplayName() const {
+  return DisplayName(kDefaultNamePriority, string16());
+}
+
+GURL BaseSettingChange::GetNewSettingURL() const {
+  return GURL();
+}
+
+bool BaseSettingChange::CanBeMerged() const {
+  // By default change can be collapsed if it has a non-empty keyword.
+  return !GetNewSettingURL().is_empty();
+}
+
 }  // namespace protector