Don't crash when trying to create an ExtensionSyncData from invalid SyncData.

chrome/browser/extensions/app_sync_data.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_APP_SYNC_DATA_H_
 #define CHROME_BROWSER_EXTENSIONS_APP_SYNC_DATA_H_
 
+#include "base/memory/scoped_ptr.h"
 #include "chrome/browser/extensions/extension_sync_data.h"
 #include "extensions/common/constants.h"
 #include "sync/api/string_ordinal.h"
 #include "sync/api/sync_change.h"
 #include "third_party/skia/include/core/SkColor.h"
 
 namespace syncer {
 class SyncData;
 }
 
 namespace sync_pb {
 class AppSpecifics;
 }
 
 namespace extensions {
 
 class Extension;
 class ExtensionSyncData;
 
 // A class that encapsulates the synced properties of an Application.
 class AppSyncData {
  public:
   AppSyncData();
-  explicit AppSyncData(const syncer::SyncData& sync_data);
-  explicit AppSyncData(const syncer::SyncChange& sync_change);
   AppSyncData(const Extension& extension,
               bool enabled,
               bool incognito_enabled,
               bool remote_install,
               ExtensionSyncData::OptionalBoolean all_urls_enabled,
               const syncer::StringOrdinal& app_launch_ordinal,
               const syncer::StringOrdinal& page_ordinal,
               extensions::LaunchType launch_type);
   ~AppSyncData();
 
+  // For constructing an AppSyncData from received sync data.

[not at google - send to devlin, 2015/03/11 23:21:34]

Mention these may be null (because...)

[Yoyo Zhou, 2015/03/12 00:25:48]

Ok. Also changed to not use the implicit constructor from null.

+  static scoped_ptr<AppSyncData> CreateFromSyncData(
+      const syncer::SyncData& sync_data);
+  static scoped_ptr<AppSyncData> CreateFromSyncChange(
+      const syncer::SyncChange& sync_change);
+
   // Retrive sync data from this class.
   syncer::SyncData GetSyncData() const;
   syncer::SyncChange GetSyncChange(
       syncer::SyncChange::SyncChangeType change_type) const;
 
   const std::string& id() const { return extension_sync_data_.id(); }
 
   bool uninstalled() const { return extension_sync_data_.uninstalled(); }
 
   // These ordinals aren't necessarily valid. Some applications don't have
@@ skipping 20 matching lines @@
   }
 
   const std::string& bookmark_app_icon_color() const {
     return bookmark_app_icon_color_;
   }
 
  private:
   // Convert an AppSyncData back out to a sync structure.
   void PopulateAppSpecifics(sync_pb::AppSpecifics* specifics) const;
 
-  // Populate this class from sync inputs.
-  void PopulateFromAppSpecifics(
-      const sync_pb::AppSpecifics& specifics);
-  void PopulateFromSyncData(const syncer::SyncData& sync_data);
+  // Populate this class from sync inputs. Return true if the input
+  // was valid.
+  bool PopulateFromAppSpecifics(const sync_pb::AppSpecifics& specifics);
+  bool PopulateFromSyncData(const syncer::SyncData& sync_data);
 
   ExtensionSyncData extension_sync_data_;
   syncer::StringOrdinal app_launch_ordinal_;
   syncer::StringOrdinal page_ordinal_;
   extensions::LaunchType launch_type_;
   std::string bookmark_app_url_;
   std::string bookmark_app_description_;
   std::string bookmark_app_icon_color_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_APP_SYNC_DATA_H_
-