Port ChromeSyncShell build rules to GN

sync/protocol/BUILD.gn

Index: sync/protocol/BUILD.gn
diff --git a/sync/protocol/BUILD.gn b/sync/protocol/BUILD.gn
index 0fefbc5831633ffec430cde46f35aae52142f959..f90ae702651dd1a8a9ae6c91996d662f3af91122 100644
--- a/sync/protocol/BUILD.gn
+++ b/sync/protocol/BUILD.gn
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//third_party/protobuf/proto_library.gni")
+import("protocol_sources.gni")
 
 # This must be a component for the dependency structure we have now, but the
 # proto_library generates a source set. Link those into a component.
@@ -15,49 +16,7 @@ component("protocol") {
 proto_library("protocol_internal") {
   visibility = [ ":protocol" ]
 
-  sources = [
-    "app_list_specifics.proto",
-    "app_notification_specifics.proto",
-    "app_setting_specifics.proto",
-    "app_specifics.proto",
-    "article_specifics.proto",
-    "attachments.proto",
-    "autofill_specifics.proto",
-    "bookmark_specifics.proto",
-    "client_commands.proto",
-    "client_debug_info.proto",
-    "device_info_specifics.proto",
-    "dictionary_specifics.proto",
-    "encryption.proto",
-    "entity_metadata.proto",
-    "experiment_status.proto",
-    "experiments_specifics.proto",
-    "extension_setting_specifics.proto",
-    "extension_specifics.proto",
-    "favicon_image_specifics.proto",
-    "favicon_tracking_specifics.proto",
-    "get_updates_caller_info.proto",
-    "history_delete_directive_specifics.proto",
-    "managed_user_setting_specifics.proto",
-    "managed_user_shared_setting_specifics.proto",
-    "managed_user_specifics.proto",
-    "managed_user_whitelist_specifics.proto",
-    "nigori_specifics.proto",
-    "password_specifics.proto",
-    "preference_specifics.proto",
-    "priority_preference_specifics.proto",
-    "search_engine_specifics.proto",
-    "session_specifics.proto",
-    "sync.proto",
-    "sync_enums.proto",
-    "synced_notification_app_info_specifics.proto",
-    "synced_notification_specifics.proto",
-    "test.proto",
-    "theme_specifics.proto",
-    "typed_url_specifics.proto",
-    "unique_position.proto",
-    "wifi_credential_specifics.proto",
-  ]
+  sources = sync_protocol_sources
 
   cc_generator_options = "dllexport_decl=SYNC_PROTO_EXPORT:"
   cc_include = "sync/protocol/sync_proto_export.h"