Use StringPiece for UTF string conversions.

base/strings/utf_string_conversions.cc

Index: base/strings/utf_string_conversions.cc
diff --git a/base/strings/utf_string_conversions.cc b/base/strings/utf_string_conversions.cc
index c3ea4f253e5b5c68bc6c1795bc354178fcda3382..0256f8ac984d139f90085716a2e8607eaf526e69 100644
--- a/base/strings/utf_string_conversions.cc
+++ b/base/strings/utf_string_conversions.cc
@@ -125,45 +125,45 @@ std::wstring UTF16ToWide(const string16& utf16) {
 
 #if defined(WCHAR_T_IS_UTF32)
 
-bool UTF8ToUTF16(const char* src, size_t src_len, string16* output) {
-  PrepareForUTF16Or32Output(src, src_len, output);
-  return ConvertUnicode(src, src_len, output);
+bool UTF8ToUTF16(const StringPiece& utf8, string16* output) {
+  PrepareForUTF16Or32Output(utf8.data(), utf8.size(), output);
+  return ConvertUnicode(utf8.data(), utf8.size(), output);
 }
 
 string16 UTF8ToUTF16(const StringPiece& utf8) {
   string16 ret;
   // Ignore the success flag of this call, it will do the best it can for
   // invalid input, which is what we want here.
-  UTF8ToUTF16(utf8.data(), utf8.length(), &ret);
+  UTF8ToUTF16(utf8, &ret);
   return ret;
 }
 
-bool UTF16ToUTF8(const char16* src, size_t src_len, std::string* output) {
-  PrepareForUTF8Output(src, src_len, output);
-  return ConvertUnicode(src, src_len, output);
+bool UTF16ToUTF8(const StringPiece16& utf16, std::string* output) {
+  PrepareForUTF8Output(utf16.data(), utf16.length(), output);
+  return ConvertUnicode(utf16.data(), utf16.length(), output);
 }
 
 std::string UTF16ToUTF8(const string16& utf16) {
   std::string ret;
   // Ignore the success flag of this call, it will do the best it can for
   // invalid input, which is what we want here.
-  UTF16ToUTF8(utf16.data(), utf16.length(), &ret);
+  UTF16ToUTF8(utf16, &ret);
   return ret;
 }
 
 #elif defined(WCHAR_T_IS_UTF16)
 // Easy case since we can use the "wide" versions we already wrote above.
 
-bool UTF8ToUTF16(const char* src, size_t src_len, string16* output) {
-  return UTF8ToWide(src, src_len, output);
+bool UTF8ToUTF16(const StringPiece& utf8, string16* output) {
+  return UTF8ToWide(utf8.data(), utf8.size(), output);
 }
 
 string16 UTF8ToUTF16(const StringPiece& utf8) {
   return UTF8ToWide(utf8);
 }
 
-bool UTF16ToUTF8(const char16* src, size_t src_len, std::string* output) {
-  return WideToUTF8(src, src_len, output);
+bool UTF16ToUTF8(const StringPiece16& utf16, std::string* output) {
+  return WideToUTF8(utf16.data(), utf16.size(), output);
 }
 
 std::string UTF16ToUTF8(const string16& utf16) {