Add URL generator / json parser for getting start_page_token of changes.

google_apis/drive/drive_api_parser.cc

Index: google_apis/drive/drive_api_parser.cc
diff --git a/google_apis/drive/drive_api_parser.cc b/google_apis/drive/drive_api_parser.cc
index 3e8975d1e4a2e7055a2897ede3b4aacd50038cca..d402687f2ee1444f7c98b1cf63ba19f0316bce20 100644
--- a/google_apis/drive/drive_api_parser.cc
+++ b/google_apis/drive/drive_api_parser.cc
@@ -211,6 +211,11 @@ const char kTeamDriveId[] = "teamDriveId";
 // https://developers.google.com/drive/v2/reference/changes/list
 const char kChangeListKind[] = "drive#changeList";
 
+// Changes StartPageToken
+// https://developers.google.com/drive/v2/reference/changes/getStartPageToken
+const char kStartPageTokenKind[] = "drive#startPageToken";
+const char kStartPageToken[] = "startPageToken";
+
 // Maps category name to enum ChangeType.
 struct ChangeTypeMap {
   ChangeResource::ChangeType type;
@@ -783,6 +788,45 @@ bool ChangeResource::GetType(const base::StringPiece& type_name,
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+// StartPageToken implementation
+
+StartPageToken::StartPageToken() {}
+
+StartPageToken::~StartPageToken() {}
+
+// static
+void StartPageToken::RegisterJSONConverter(
+    base::JSONValueConverter<StartPageToken>* converter) {
+  converter->RegisterStringField(kStartPageToken,
+                                 &StartPageToken::start_page_token_);
+}
+
+// static
+bool StartPageToken::HasStartPageTokenKind(const base::Value& value) {
+  return IsResourceKindExpected(value, kStartPageTokenKind);
+}
+
+// static
+std::unique_ptr<StartPageToken> StartPageToken::CreateFrom(
+    const base::Value& value) {
+  std::unique_ptr<StartPageToken> resource(new StartPageToken());
+  if (!HasStartPageTokenKind(value) || !resource->Parse(value)) {
+    LOG(ERROR) << "Unable to create: Invalid StartPageToken JSON!";
+    return std::unique_ptr<StartPageToken>();
+  }
+  return resource;
+}
+
+bool StartPageToken::Parse(const base::Value& value) {
+  base::JSONValueConverter<StartPageToken> converter;
+  if (!converter.Convert(value, this)) {
+    LOG(ERROR) << "Unable to parse: Invalid StartPageToken";
+    return false;
+  }
+  return true;
+}
+
+////////////////////////////////////////////////////////////////////////////////
 // ChangeList implementation
 
 ChangeList::ChangeList() : largest_change_id_(0) {}