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..48597b586e89b677725ee3ae798cc69296e9cdde 100644
--- a/chrome/browser/google_apis/gdata_wapi_parser.h
+++ b/chrome/browser/google_apis/gdata_wapi_parser.h
@@ -384,8 +384,15 @@ class DocumentEntry : public FeedEntry {
 
   // Helper function for parsing bool fields based on presence of
   // their value nodes.
+  // Returns true even when |value| is NULL.
   static bool HasFieldPresent(const base::Value* value, bool* result);
 
+  // Helper function for parsing changestamp. If the field does not exists,
+  // this function sets the changestamp to 0.
+  // Returns true even when |value| is NULL.
+  static bool ParseOptionalChangestamp(const base::StringPiece& value,
+                                       int64* result);
+
   // Returns true if |file| has one of the hosted document extensions.
   static bool HasHostedDocumentExtension(const FilePath& file);
 
@@ -434,6 +441,9 @@ 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).
+  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 +527,7 @@ class DocumentEntry : public FeedEntry {
   int64 file_size_;
   bool deleted_;
   bool removed_;
+  int64 changestamp_;
 
   DISALLOW_COPY_AND_ASSIGN(DocumentEntry);
 };