Move StringToLowerASCII to base namespace

pdf/pdfium/pdfium_page.cc

Index: pdf/pdfium/pdfium_page.cc
diff --git a/pdf/pdfium/pdfium_page.cc b/pdf/pdfium/pdfium_page.cc
index f7656ed7161a09aa880b0368ebebbd2b378eca32..3012fad9c82d73b5ef5579001b16216ee8fdb032 100644
--- a/pdf/pdfium/pdfium_page.cc
+++ b/pdf/pdfium/pdfium_page.cc
@@ -189,8 +189,8 @@ base::Value* PDFiumPage::GetTextBoxAsValue(double page_height,
       DCHECK(targets[i].url[targets[i].url.size() - 1] != '\0');
 
       // PDFium may change the case of generated links.
-      std::string lowerCaseURL = StringToLowerASCII(targets[i].url);
-      std::string lowerCaseText = StringToLowerASCII(text_utf8);
+      std::string lowerCaseURL = base::StringToLowerASCII(targets[i].url);
+      std::string lowerCaseText = base::StringToLowerASCII(text_utf8);
       size_t pos = lowerCaseText.find(lowerCaseURL, start);
       size_t length = targets[i].url.size();
       if (pos == std::string::npos) {