Make UTF16ToASCII and UTF16TOUTF8 take a StringPiece

android_webview/renderer/aw_render_view_ext.cc

Index: android_webview/renderer/aw_render_view_ext.cc
diff --git a/android_webview/renderer/aw_render_view_ext.cc b/android_webview/renderer/aw_render_view_ext.cc
index b91b8abfe3aa18c50b15748276a9c1c614686253..ac377253e24b3351b7f070fbfae5bff3e26ffbf6 100644
--- a/android_webview/renderer/aw_render_view_ext.cc
+++ b/android_webview/renderer/aw_render_view_ext.cc
@@ -80,9 +80,8 @@ bool RemovePrefixAndAssignIfMatches(const base::StringPiece& prefix,
     url::DecodeURLEscapeSequences(spec.data() + prefix.length(),
                                   spec.length() - prefix.length(),
                                   &output);
-    std::string decoded_url = base::UTF16ToUTF8(
-        base::string16(output.data(), output.length()));
-    dest->assign(decoded_url.begin(), decoded_url.end());
+    *dest = base::UTF16ToUTF8(
+        base::StringPiece16(output.data(), output.length()));
     return true;
   }
   return false;