Handle long press in PDF documents.

pdf/preview_mode_client.cc

Index: pdf/preview_mode_client.cc
diff --git a/pdf/preview_mode_client.cc b/pdf/preview_mode_client.cc
index b3744c93eb7ac81b0de4f9b0d604cd07cfe8c465..4a0f169737e474c00d66592222d17d76026d9804 100644
--- a/pdf/preview_mode_client.cc
+++ b/pdf/preview_mode_client.cc
@@ -118,6 +118,10 @@ void PreviewModeClient::ScheduleCallback(int id, int delay_in_ms) {
   NOTREACHED();
 }
 
+void PreviewModeClient::ScheduleTouchTimerCallback(int id, int delay_in_ms) {
+  NOTREACHED();
+}
+
 void PreviewModeClient::SearchString(const base::char16* string,
                                      const base::char16* term,
                                      bool case_sensitive,