This is a sample code to upload a PDF file to Google Drive with OCR in Apps Script. uploadPdfOcr function returns a File object. To run the code provide a developer key for an API Console project with Drive API service enabled.

DriveUpload.gs

function uploadPdfOcr() {
  authorize();
  var key = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"; // <-- developer key
  var file = UrlFetchApp.fetch("http://somewhere.com/path/file.pdf").getBlob();
  var metadata = { title: file.getName() }
  var params = {method:"post",
                oAuthServiceName: "drive",
                oAuthUseToken: "always",
                contentType: "application/pdf",
                contentLength: file.getBytes().length,
                payload: file.getBytes()
               };
  var uploadRequest = UrlFetchApp.fetch("https://www.googleapis.com/upload/drive/v2/files/?uploadType=media&ocr=true&key="+key, params);
  var uploadResponse = Utilities.jsonParse(uploadRequest.getContentText());
  var params = {method:"put",
                oAuthServiceName: "drive",
                oAuthUseToken: "always",
                contentType: "application/json",
                payload: Utilities.jsonStringify(metadata)
               };
  var metaRequest = UrlFetchApp.fetch("https://www.googleapis.com/drive/v2/files/"+uploadResponse.id+"?key="+key, params)
  return DocsList.getFileById(uploadResponse.id);
}

function convert(fileId) {
  authorize();
  var key = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"; // <-- developer key
  var params = {method:"post",
                oAuthServiceName: "drive",
                oAuthUseToken: "always"
               };
  var uploadRequest = UrlFetchApp.fetch("https://www.googleapis.com/drive/v2/files/"+fileId+"/copy?convert=true&key="+key, params);
  var uploadResponse = Utilities.jsonParse(uploadRequest.getContentText());
  return DocsList.getFileById(uploadResponse.id);
}

function authorize() {
  var oauthConfig = UrlFetchApp.addOAuthService("drive");
  var scope = "https://www.googleapis.com/auth/drive";
  oauthConfig.setConsumerKey("anonymous");
  oauthConfig.setConsumerSecret("anonymous");
  oauthConfig.setRequestTokenUrl("https://www.google.com/accounts/OAuthGetRequestToken?scope="+scope);
  oauthConfig.setAuthorizationUrl("https://accounts.google.com/OAuthAuthorizeToken");    
  oauthConfig.setAccessTokenUrl("https://www.google.com/accounts/OAuthGetAccessToken");  
}