Fix failed to write thumbnail png issue

media/gpu/video_decode_accelerator_unittest.cc

Index: media/gpu/video_decode_accelerator_unittest.cc
diff --git a/media/gpu/video_decode_accelerator_unittest.cc b/media/gpu/video_decode_accelerator_unittest.cc
index 16f528e93d469753863e73d1c45a9279546442a5..76fc18c6b21bba8e4d3c0d0d484fadafd5f013f9 100644
--- a/media/gpu/video_decode_accelerator_unittest.cc
+++ b/media/gpu/video_decode_accelerator_unittest.cc
@@ -199,6 +199,8 @@ const int kMD5StringLength = 32;
 base::FilePath GetTestDataFile(const base::FilePath& input_file) {
   if (input_file.IsAbsolute())
     return input_file;
+  // input_file needs to be existed, otherwise base::MakeAbsoluteFilePath will
+  // return an empty base::FilePath.

[Owen Lin, 2017/03/15 08:41:43]

Sounds like we should fail the test and LOG(FATAL) the information.

[johnylin1, 2017/03/15 14:06:16]

Done.

   return base::MakeAbsoluteFilePath(g_test_file_path.Append(input_file));
 }
 
@@ -1540,11 +1542,11 @@ TEST_P(VideoDecodeAcceleratorParamTest, TestSimpleDecode) {
       LOG(ERROR) << "Unknown thumbnails MD5: " << md5_string;
 
       base::FilePath filepath(test_video_files_[0]->file_name);
+      filepath = GetTestDataFile(filepath);

[Owen Lin, 2017/03/15 08:41:43]

I would suggest to allow user to configure the output directory. So that we can
save the output png files in autotest's result dir.

[johnylin1, 2017/03/15 14:06:15]

Done.

       filepath = filepath.AddExtension(FILE_PATH_LITERAL(".bad_thumbnails"));
       filepath = filepath.AddExtension(FILE_PATH_LITERAL(".png"));
-      int num_bytes =
-          base::WriteFile(GetTestDataFile(filepath),
-                          reinterpret_cast<char*>(&png[0]), png.size());
+      int num_bytes = base::WriteFile(
+          filepath, reinterpret_cast<char*>(&png[0]), png.size());
       EXPECT_EQ(num_bytes, static_cast<int>(png.size()));
     }
     EXPECT_NE(match, golden_md5s.end());