Pass a const char* argument to IVFVideoSource ctor

Pass a const char* argument to the IVFVideoSource constructor. It is not
necessary to create a std::string local variable and pass it to the
IVFVideoSource constructor.

Change-Id: I02f8a6a2882792c6db1a944f69bb2f5e19e076ab
diff --git a/test/decode_scalability_test.cc b/test/decode_scalability_test.cc
index 6dea8bf..4817beb 100644
--- a/test/decode_scalability_test.cc
+++ b/test/decode_scalability_test.cc
@@ -10,7 +10,6 @@
  */
 
 #include <ostream>
-#include <string>
 
 #include "test/codec_factory.h"
 #include "test/decode_test_driver.h"
@@ -63,8 +62,7 @@
   void RunTest() {
     const DecodeParam input = GET_PARAM(1);
     aom_codec_dec_cfg_t cfg = { 1, 0, 0, !FORCE_HIGHBITDEPTH_DECODING };
-    const std::string filename = input.filename;
-    libaom_test::IVFVideoSource decode_video(filename);
+    libaom_test::IVFVideoSource decode_video(input.filename);
     decode_video.Init();
 
     ASSERT_NO_FATAL_FAILURE(RunLoop(&decode_video, cfg));
diff --git a/test/invalid_file_test.cc b/test/invalid_file_test.cc
index 6ac8d1a..acc8986 100644
--- a/test/invalid_file_test.cc
+++ b/test/invalid_file_test.cc
@@ -103,8 +103,7 @@
     const DecodeParam input = GET_PARAM(1);
     aom_codec_dec_cfg_t cfg = { 0, 0, 0, !FORCE_HIGHBITDEPTH_DECODING };
     cfg.threads = input.threads;
-    const std::string filename = input.filename;
-    libaom_test::IVFVideoSource decode_video(filename);
+    libaom_test::IVFVideoSource decode_video(input.filename);
     decode_video.Init();
 
     // The result file holds a list of expected integer results, one for each