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 3938c97cf1e15a0ccbd458bfe09acc398f83c157..677ce024496275481843df095183aa131b51dbba 100644
--- a/pdf/preview_mode_client.cc
+++ b/pdf/preview_mode_client.cc
@@ -115,6 +115,10 @@ 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,