Prevent guest views from issuing a search for empty text.

pdf/pdfium/pdfium_engine.h

Index: pdf/pdfium/pdfium_engine.h
diff --git a/pdf/pdfium/pdfium_engine.h b/pdf/pdfium/pdfium_engine.h
index 4cf49cd248b3d044ea1425a7e4323da3a7f0bb30..7d39108916ed1be6950c8637e60f0c1a471efee8 100644
--- a/pdf/pdfium/pdfium_engine.h
+++ b/pdf/pdfium/pdfium_engine.h
@@ -66,7 +66,7 @@ class PDFiumEngine : public PDFEngine,
       uint32_t page_range_count,
       const PP_PrintSettings_Dev& print_settings);
   virtual void PrintEnd();
-  virtual void StartFind(const char* text, bool case_sensitive);
+  virtual void StartFind(const std::string& text, bool case_sensitive);
   virtual bool SelectFindResult(bool forward);
   virtual void StopFind();
   virtual void ZoomUpdated(double new_zoom_level);