Revert "Reland "[Chromecast] Update mixer unittests""

This reverts commit 07c7facb.

Reason for revert: Caused build error

https://ci.chromium.org/buildbot/chromium.linux/Fuchsia%20ARM64%20Cast%20Audio/5780
../../chromecast/media/cma/backend/stream_mixer_unittest.cc:423:13: error: unused function 'DeathRegex' [-Werror,-Wunused-function]
std::string DeathRegex(const std::string& regex) {
            ^
1 error generated.

Original change's description:
> Reland "[Chromecast] Update mixer unittests"
> 
> This reverts commit d0ca87de.
> 
> Added ifdef guard for death tests.
> 
> Bug: internal b/71559266
> Change-Id: I204a00d7a1759a4a18407f5162843366e9229da5
> Reviewed-on: https://chromium-review.googlesource.com/941789
> Reviewed-by: Scott Graham <scottmg@chromium.org>
> Reviewed-by: Luke Halliwell <halliwell@chromium.org>
> Commit-Queue: Kenneth MacKay <kmackay@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#539976}

TBR=halliwell@chromium.org,scottmg@chromium.org,kmackay@chromium.org

Change-Id: I05ba642b66d4bb1e2f1eb8fe8e86c705b361a9a8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: internal b/71559266
Reviewed-on: https://chromium-review.googlesource.com/942422Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Commit-Queue: Tsuyoshi Horo <horo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539981}

chromecast/media/cma/backend/BUILD.gn

@@ -175,11 +175,11 @@ cast_source_set("for_mixer_audio") {
 test("cast_audio_backend_unittests") {
   testonly = true
   sources = [
-    "audio_fader_unittest.cc",
     "filter_group_unittest.cc",
     "mock_mixer_source.cc",
     "mock_mixer_source.h",
-    "stream_mixer_unittest.cc",
+
+    # "stream_mixer_unittest.cc",
   ]
 
   deps = [

chromecast/media/cma/backend/audio_fader.cc

@@ -84,8 +84,7 @@ void AudioFader::CompleteFill(::media::AudioBus* buffer, int filled_frames) {
     case State::kFadingOut:
       // Fade back in.
       state_ = State::kFadingIn;
-      fade_frames_remaining_ =
-          std::max(0, fade_frames_ - fade_frames_remaining_ - 1);
+      fade_frames_remaining_ = fade_frames_ - fade_frames_remaining_;
       break;
   }
   FadeIn(buffer, filled_frames);
@@ -101,8 +100,7 @@ void AudioFader::IncompleteFill(::media::AudioBus* buffer, int filled_frames) {
     case State::kFadingIn:
       // Fade back out.
       state_ = State::kFadingOut;
-      fade_frames_remaining_ =
-          std::max(0, fade_frames_ - fade_frames_remaining_ - 1);
+      fade_frames_remaining_ = fade_frames_ - fade_frames_remaining_;
       break;
     case State::kPlaying:
       // Fade out.