Print more info in IsStringASCII assertions.

base/string_util.cc

Index: base/string_util.cc
diff --git a/base/string_util.cc b/base/string_util.cc
index b456376ee4460d10de3ecfb45fbdbb112a504fa5..f58f105ee1653b6a9ec83948d9243b3073c300bf 100644
--- a/base/string_util.cc
+++ b/base/string_util.cc
@@ -502,22 +502,22 @@ std::string CollapseWhitespaceASCII(const std::string& text,
 }
 
 std::string WideToASCII(const std::wstring& wide) {
-  DCHECK(IsStringASCII(wide));
+  DCHECK(IsStringASCII(wide)) << wide;
   return std::string(wide.begin(), wide.end());
 }
 
 std::wstring ASCIIToWide(const StringPiece& ascii) {
-  DCHECK(IsStringASCII(ascii));
+  DCHECK(IsStringASCII(ascii)) << ascii;
   return std::wstring(ascii.begin(), ascii.end());
 }
 
 std::string UTF16ToASCII(const string16& utf16) {
-  DCHECK(IsStringASCII(utf16));
+  DCHECK(IsStringASCII(utf16)) << utf16;
   return std::string(utf16.begin(), utf16.end());
 }
 
 string16 ASCIIToUTF16(const StringPiece& ascii) {
-  DCHECK(IsStringASCII(ascii));
+  DCHECK(IsStringASCII(ascii)) << ascii;
   return string16(ascii.begin(), ascii.end());
 }