Prevent guest views from issuing a search for empty text.

pdf/pdf_engine.h

Index: pdf/pdf_engine.h
diff --git a/pdf/pdf_engine.h b/pdf/pdf_engine.h
index 69761a16b76cd691ba7727d79f6366b6260e26ea..7cde54aaf64e1f8cb965539ee9a5cf6940b47776 100644
--- a/pdf/pdf_engine.h
+++ b/pdf/pdf_engine.h
@@ -209,7 +209,7 @@ class PDFEngine {
       uint32_t page_range_count,
       const PP_PrintSettings_Dev& print_settings) = 0;
   virtual void PrintEnd() = 0;
-  virtual void StartFind(const char* text, bool case_sensitive) = 0;
+  virtual void StartFind(const std::string& text, bool case_sensitive) = 0;
   virtual bool SelectFindResult(bool forward) = 0;
   virtual void StopFind() = 0;
   virtual void ZoomUpdated(double new_zoom_level) = 0;