media/gpu/VDTest: Don't save frames in ALLOCATE mode

VideoFrameFileWriter cannot save frames in ALLOCATE mode because the video frame
cannot be mapped. This CL fixes the failure in FlushAtEndOfStream_Allocate with
--output_frames option.

Bug: None
Test: video_decode_accelerator_tests with --output_frames
Change-Id: I9ea023c182d010fa65621c428c6291912ffd6db2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1777844
Auto-Submit: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: David Staessens <dstaessens@chromium.org>
Commit-Queue: David Staessens <dstaessens@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692026}

media/gpu/video_decode_accelerator_tests.cc

@@ -74,8 +74,10 @@ class VideoDecoderTest : public ::testing::Test {
           media::test::VideoFrameValidator::Create(video->FrameChecksums()));
     }
 
-    // Write decoded video frames to the '<testname>' folder.
-    if (g_env->IsFramesOutputEnabled()) {
+    // Write decoded video frames to the '<testname>' folder if import mode is
+    // supported and enabled.
+    if (g_env->IsFramesOutputEnabled() &&
+        config.allocation_mode == AllocationMode::kImport) {
       base::FilePath output_folder =
           base::FilePath(g_env->OutputFolder())
               .Append(base::FilePath(g_env->GetTestName()));