Implement polling part of DriveFileSyncService

chrome/browser/google_apis/gdata_wapi_parser.h

Index: chrome/browser/google_apis/gdata_wapi_parser.h
diff --git a/chrome/browser/google_apis/gdata_wapi_parser.h b/chrome/browser/google_apis/gdata_wapi_parser.h
index 684b219b70f6230eb552a7b39ddcc86e2655d765..99395e1a683ee1b8ebc0bad2aa287fe44283d489 100644
--- a/chrome/browser/google_apis/gdata_wapi_parser.h
+++ b/chrome/browser/google_apis/gdata_wapi_parser.h
@@ -382,10 +382,15 @@ class DocumentEntry : public FeedEntry {
   static void RegisterJSONConverter(
       base::JSONValueConverter<DocumentEntry>* converter);
 
-  // Helper function for parsing bool fields based on presence of
-  // their value nodes.
+  // Sets true to |result| if the field exists.
+  // Always returns true even when the field does not exist.
   static bool HasFieldPresent(const base::Value* value, bool* result);
 
+  // Parses |value| as int64 and sets it to |result|. If the field does not
+  // exist, sets 0 to |result| as default value.
+  // Returns true if |value| is NULL or it is parsed as int64 successfully.
+  static bool ParseChangestamp(const base::Value* value, int64* result);
+
   // Returns true if |file| has one of the hosted document extensions.
   static bool HasHostedDocumentExtension(const FilePath& file);
 
@@ -434,6 +439,10 @@ class DocumentEntry : public FeedEntry {
   // True if the file or directory is deleted (applicable to change feeds only).
   bool deleted() const { return deleted_ || removed_; }
 
+  // Changestamp (exists only for change query results).
+  // If not exists, defaults to 0.
+  int64 changestamp() const { return changestamp_; }
+
   // Text version of document entry kind. Returns an empty string for
   // unknown entry kind.
   std::string GetEntryKindText() const;
@@ -517,6 +526,7 @@ class DocumentEntry : public FeedEntry {
   int64 file_size_;
   bool deleted_;
   bool removed_;
+  int64 changestamp_;
 
   DISALLOW_COPY_AND_ASSIGN(DocumentEntry);
 };