Use String8/16 c_str [media]

Bug: 295394788
Test: make checkbuild
Change-Id: I4ba5400f39c769bec59508525844f1daefe1d15c
diff --git a/media/libmedia/IMediaHTTPConnection.cpp b/media/libmedia/IMediaHTTPConnection.cpp
index 8cbb4c2..b029b97 100644
--- a/media/libmedia/IMediaHTTPConnection.cpp
+++ b/media/libmedia/IMediaHTTPConnection.cpp
@@ -54,8 +54,8 @@
         tmp = String16("");
         if (headers != NULL) {
             for (size_t i = 0; i < headers->size(); ++i) {
-                String16 key(headers->keyAt(i).string());
-                String16 val(headers->valueAt(i).string());
+                String16 key(headers->keyAt(i).c_str());
+                String16 val(headers->valueAt(i).c_str());
 
                 tmp.append(key);
                 tmp.append(String16(": "));