Use StringPiece for UTF string conversions.

base/android/jni_string.cc

Index: base/android/jni_string.cc
diff --git a/base/android/jni_string.cc b/base/android/jni_string.cc
index d25fed822bc3dbea5d3abd294763335e88acf966..105a902ccc4e0b3972cc85dd24aa0374a3f7fee7 100644
--- a/base/android/jni_string.cc
+++ b/base/android/jni_string.cc
@@ -34,7 +34,7 @@ void ConvertJavaStringToUTF8(JNIEnv* env, jstring str, std::string* result) {
   // function that yields plain (non Java-modified) UTF8.
   const jchar* chars = env->GetStringChars(str, NULL);
   DCHECK(chars);
-  UTF16ToUTF8(chars, env->GetStringLength(str), result);
+  UTF16ToUTF8(base::StringPiece(chars, env->GetStringLength(str)), result);
   env->ReleaseStringChars(str, chars);
   CheckException(env);
 }