Print preview: Use an ID instead of memory pointer string in WebUI.

BUG=144051

Review URL: https://chromiumcodereview.appspot.com/10870003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@153342 0039d316-1c4b-4281-b951-d872f2087c98
void PrintingMessageFilter::OnCheckForCancel(const std::string& preview_ui_addr,
void PrintingMessageFilter::OnCheckForCancel(int32 preview_ui_id,
                                              int preview_request_id,
                                              bool* cancel) {
  PrintPreviewUI::GetCurrentPrintPreviewStatus(preview_ui_id,
                                                preview_request_id,
                                                cancel);
 }

void PrintingMessageFilter::OnCheckForCancel(const std::string& preview_ui_addr,
                                              int preview_request_id,
                                              bool* cancel) {
  PrintPreviewUI::GetCurrentPrintPreviewStatus(preview_ui_addr,
                                                preview_request_id,
                                                cancel);
 }
