Clean up URL test string conversions.

Originally the url test utils had UTF string conversion functions because we
didn't want the library to depend on STL (for embedders). We've not had this
limitation for a long time so the UTF16 <--> UTF8 conversion functions can be
deleted in favor of the ones in base.

The one remaining function which generates possibly-invalid UTF16 (by design)
is renamed and clarified for this purpose.

Review-Url: https://codereview.chromium.org/2469133002
Cr-Commit-Position: refs/heads/master@{#429688}
diff --git a/url/url_canon_icu_unittest.cc b/url/url_canon_icu_unittest.cc
index 13601f0..af320f9 100644
--- a/url/url_canon_icu_unittest.cc
+++ b/url/url_canon_icu_unittest.cc
@@ -14,8 +14,6 @@
 
 namespace url {
 
-using test_utils::WStringToUTF16;
-
 namespace {
 
 // Wrapper around a UConverter object that managers creation and destruction.
@@ -64,7 +62,8 @@
     std::string str;
     StdStringCanonOutput output(&str);
 
-    base::string16 input_str(WStringToUTF16(icu_cases[i].input));
+    base::string16 input_str(
+        test_utils::TruncateWStringToUTF16(icu_cases[i].input));
     int input_len = static_cast<int>(input_str.length());
     converter.ConvertFromUTF16(input_str.c_str(), input_len, &output);
     output.Complete();
@@ -134,7 +133,8 @@
     }
 
     if (query_cases[i].input16) {
-      base::string16 input16(WStringToUTF16(query_cases[i].input16));
+      base::string16 input16(
+          test_utils::TruncateWStringToUTF16(query_cases[i].input16));
       int len = static_cast<int>(input16.length());
       Component in_comp(0, len);
       std::string out_str;