Add a getNavigation request for plugins

pkg/analyzer_plugin/lib/protocol/protocol_constants.dart

Index: pkg/analyzer_plugin/lib/protocol/protocol_constants.dart
diff --git a/pkg/analyzer_plugin/lib/protocol/protocol_constants.dart b/pkg/analyzer_plugin/lib/protocol/protocol_constants.dart
index f54687c2605243a964850cb502fe33e490a71b5d..bd8e54ee2ecf49923b8b15cba92e099a5326d4b5 100644
--- a/pkg/analyzer_plugin/lib/protocol/protocol_constants.dart
+++ b/pkg/analyzer_plugin/lib/protocol/protocol_constants.dart
@@ -26,6 +26,10 @@ const String ANALYSIS_NOTIFICATION_OCCURRENCES_OCCURRENCES = 'occurrences';
 const String ANALYSIS_NOTIFICATION_OUTLINE = 'analysis.outline';
 const String ANALYSIS_NOTIFICATION_OUTLINE_FILE = 'file';
 const String ANALYSIS_NOTIFICATION_OUTLINE_OUTLINE = 'outline';
+const String ANALYSIS_REQUEST_GET_NAVIGATION = 'analysis.getNavigation';
+const String ANALYSIS_REQUEST_GET_NAVIGATION_FILE = 'file';
+const String ANALYSIS_REQUEST_GET_NAVIGATION_LENGTH = 'length';
+const String ANALYSIS_REQUEST_GET_NAVIGATION_OFFSET = 'offset';
 const String ANALYSIS_REQUEST_HANDLE_WATCH_EVENTS =
     'analysis.handleWatchEvents';
 const String ANALYSIS_REQUEST_HANDLE_WATCH_EVENTS_EVENTS = 'events';
@@ -42,6 +46,9 @@ const String ANALYSIS_REQUEST_SET_SUBSCRIPTIONS = 'analysis.setSubscriptions';
 const String ANALYSIS_REQUEST_SET_SUBSCRIPTIONS_SUBSCRIPTIONS = 'subscriptions';
 const String ANALYSIS_REQUEST_UPDATE_CONTENT = 'analysis.updateContent';
 const String ANALYSIS_REQUEST_UPDATE_CONTENT_FILES = 'files';
+const String ANALYSIS_RESPONSE_GET_NAVIGATION_FILES = 'files';
+const String ANALYSIS_RESPONSE_GET_NAVIGATION_REGIONS = 'regions';
+const String ANALYSIS_RESPONSE_GET_NAVIGATION_TARGETS = 'targets';
 const String COMPLETION_REQUEST_GET_SUGGESTIONS = 'completion.getSuggestions';
 const String COMPLETION_REQUEST_GET_SUGGESTIONS_FILE = 'file';
 const String COMPLETION_REQUEST_GET_SUGGESTIONS_OFFSET = 'offset';