Allow pdfium_test to send simple events to each page.

testing/test_support.h

Index: testing/test_support.h
diff --git a/testing/test_support.h b/testing/test_support.h
index 4b716ae7720871965a937e67d9f7e42440da303a..aa7676d939a0fbe08d1ce4664f57800eb818ff64 100644
--- a/testing/test_support.h
+++ b/testing/test_support.h
@@ -63,6 +63,8 @@ struct FreeDeleter {
 std::unique_ptr<char, pdfium::FreeDeleter> GetFileContents(const char* filename,
                                                            size_t* retlen);
 
+std::vector<std::string> StringSplit(const std::string& str, char delimiter);
+
 // Converts a FPDF_WIDESTRING to a std::wstring.
 // Deals with differences between UTF16LE and wchar_t.
 std::wstring GetPlatformWString(const FPDF_WIDESTRING wstr);