diff --git a/third_party/blink/common/BUILD.gn b/third_party/blink/common/BUILD.gn
index 9e641e1c80e546..78e731f5abb344 100644
--- a/third_party/blink/common/BUILD.gn
+++ b/third_party/blink/common/BUILD.gn
@@ -286,7 +286,7 @@ source_set("common") {
     deps += [ "//ui/gfx/" ]
   }
 
-  if (is_chromeos || is_android || is_win || is_chromecast || is_fuchsia) {
+  if (is_chromeos || is_android || is_win || is_castos || is_fuchsia) {
     defines = [ "ENABLE_PROTECTED_MEDIA_IDENTIFIER_PERMISSION" ]
   }
 }
diff --git a/third_party/blink/renderer/modules/mediastream/media_stream_audio_processor_test.cc b/third_party/blink/renderer/modules/mediastream/media_stream_audio_processor_test.cc
index b978673bcc9fe9..ba348a79b863f6 100644
--- a/third_party/blink/renderer/modules/mediastream/media_stream_audio_processor_test.cc
+++ b/third_party/blink/renderer/modules/mediastream/media_stream_audio_processor_test.cc
@@ -240,6 +240,8 @@ TEST_P(MediaStreamAudioProcessorTestMultichannel, MAYBE_TestAllSampleRates) {
       new rtc::RefCountedObject<WebRtcAudioDeviceImpl>());
   blink::AudioProcessingProperties properties;
 
+  // TODO(crbug.com/1334991): Clarify WebRTC audio processing support for 96 kHz
+  // input.
   static const int kSupportedSampleRates[] = {
     8000,
     16000,
@@ -247,10 +249,10 @@ TEST_P(MediaStreamAudioProcessorTestMultichannel, MAYBE_TestAllSampleRates) {
     32000,
     44100,
     48000
-#if BUILDFLAG(IS_CHROMECAST)
+#if BUILDFLAG(IS_CASTOS) || BUILDFLAG(IS_CAST_ANDROID)
     ,
     96000
-#endif  // BUILDFLAG(IS_CHROMECAST)
+#endif  // BUILDFLAG(IS_CASTOS) || BUILDFLAG(IS_CAST_ANDROID)
   };
   for (int sample_rate : kSupportedSampleRates) {
     SCOPED_TRACE(testing::Message() << "sample_rate=" << sample_rate);
@@ -266,12 +268,14 @@ TEST_P(MediaStreamAudioProcessorTestMultichannel, MAYBE_TestAllSampleRates) {
     EXPECT_TRUE(audio_processor->has_webrtc_audio_processing());
     VerifyDefaultComponents(*audio_processor);
 
+    // TODO(crbug.com/1336055): Investigate why chromecast devices need special
+    // logic here.
     int expected_sample_rate =
-#if BUILDFLAG(IS_CHROMECAST)
+#if BUILDFLAG(IS_CASTOS) || BUILDFLAG(IS_CAST_ANDROID)
         std::min(sample_rate, media::kAudioProcessingSampleRateHz);
 #else
         media::kAudioProcessingSampleRateHz;
-#endif  // BUILDFLAG(IS_CHROMECAST)
+#endif  // BUILDFLAG(IS_CASTOS) || BUILDFLAG(IS_CAST_ANDROID)
     const int expected_output_channels =
         use_multichannel_processing ? params_.channels() : 1;
     ProcessDataAndVerifyFormat(*audio_processor, mock_capture_callback_,
diff --git a/third_party/chromevox/BUILD.gn b/third_party/chromevox/BUILD.gn
index ba6ed1303c42df..d3c138186760c4 100644
--- a/third_party/chromevox/BUILD.gn
+++ b/third_party/chromevox/BUILD.gn
@@ -4,7 +4,7 @@
 import("//build/config/chromeos/ui_mode.gni")
 import("//chromecast/chromecast.gni")
 
-assert(is_chromeos_ash || is_chromecast)
+assert(is_chromeos_ash || is_castos)
 
 chromevox_out_dir = "$root_out_dir/resources/chromeos/accessibility/chromevox"
 
diff --git a/third_party/expat/BUILD.gn b/third_party/expat/BUILD.gn
index 93ce32b1413980..eee80a6bd81946 100644
--- a/third_party/expat/BUILD.gn
+++ b/third_party/expat/BUILD.gn
@@ -9,7 +9,7 @@ import("//testing/libfuzzer/fuzzer_test.gni")
 # let's not pull it in twice.
 # Chromecast doesn't ship expat as a system library.
 # Libfuzzer and AFL need to build library from sources.
-if ((is_linux || is_chromeos) && !is_chromecast && !use_fuzzing_engine) {
+if (((is_linux && !is_castos) || is_chromeos) && !use_fuzzing_engine) {
   config("expat_config") {
     libs = [ "expat" ]
   }
diff --git a/third_party/freetype-testing/BUILD.gn b/third_party/freetype-testing/BUILD.gn
index e02d8dec145ea1..e39b85631bbdc2 100644
--- a/third_party/freetype-testing/BUILD.gn
+++ b/third_party/freetype-testing/BUILD.gn
@@ -128,7 +128,7 @@ source_set("freetype_fuzzer_sources") {
     "$_src/visitors/glyphvisitor.h",
   ]
 
-  if (is_linux || is_chromeos || is_chromecast) {
+  if (is_linux || is_chromeos || is_cast_android) {
     # These sources depend on FreeType's symbol FT_Get_BDF_Charset_ID which is only built on this
     # configuration/platforms, see FreeType's BUILD.gn. In turn they will only be needed by the BDF fuzzer that we built only on this configuration/platforms.
     sources += [
@@ -282,7 +282,7 @@ freetype_fuzzer_test("type1_render") {
   dict = "src/fuzzing/settings/oss-fuzz/type1.dict"
 }
 
-if (is_linux || is_chromeos || is_chromecast) {
+if (is_linux || is_chromeos || is_cast_android) {
   # FreeType's symbol FT_Get_BDF_Charset_ID is only built on this
   # configuration, see FreeType's BUILD.gn. So build fuzzers that depend on
   # this symbol only on this configuration, too.
diff --git a/third_party/freetype/BUILD.gn b/third_party/freetype/BUILD.gn
index 7769b514cab1a8..0750dd17e35ab8 100644
--- a/third_party/freetype/BUILD.gn
+++ b/third_party/freetype/BUILD.gn
@@ -132,7 +132,7 @@ source_set("freetype_source") {
     ]
   }
 
-  if (is_linux || is_chromeos || is_chromecast) {
+  if (is_linux || is_chromeos || is_cast_android) {
     # Needed for content_shell on Linux and Chromecast, since fontconfig
     # requires FT_Get_BDF_Property.
     sources += [ "src/src/base/ftbdf.c" ]
diff --git a/third_party/libaom/options.gni b/third_party/libaom/options.gni
index 9ccf12e535ef36..b72b0cb5d3486f 100644
--- a/third_party/libaom/options.gni
+++ b/third_party/libaom/options.gni
@@ -4,7 +4,7 @@ import("//build/config/gclient_args.gni")
 
 declare_args() {
   # Enable encoding and decoding AV1 video files.
-  enable_libaom = !is_chromeos_lacros && !is_android && !is_chromecast
+  enable_libaom = !is_chromeos_lacros && !is_android && !is_castos
 
   # To be deprecated soon.
   enable_libaom_decoder = false
diff --git a/third_party/liblouis/BUILD.gn b/third_party/liblouis/BUILD.gn
index a8b83479dd5021..b16ca707a0b25e 100644
--- a/third_party/liblouis/BUILD.gn
+++ b/third_party/liblouis/BUILD.gn
@@ -9,7 +9,7 @@ liblouis_library("liblouis") {
   dest_dir = "$root_build_dir/resources/chromeos/accessibility/chromevox/background/braille"
 }
 
-if (!is_chromecast) {
+if (!is_castos) {
   chromevox_test_data_dir = "$root_build_dir/chromevox_test_data/braille"
 
   liblouis_library("liblouis_test_data") {
diff --git a/third_party/minigbm/BUILD.gn b/third_party/minigbm/BUILD.gn
index 02466e8a5cca44..f70eccc6f961c9 100644
--- a/third_party/minigbm/BUILD.gn
+++ b/third_party/minigbm/BUILD.gn
@@ -12,7 +12,7 @@ declare_args() {
   # Controls whether the build should use the version of minigbm library shipped
   # with the system. In release builds of desktop Linux and Chrome OS we use the
   # system version.
-  use_system_minigbm = (is_linux && !is_chromecast) || is_chromeos_lacros
+  use_system_minigbm = (is_linux && !is_castos) || is_chromeos_lacros
 
   use_amdgpu_minigbm = false
   use_exynos_minigbm = false
diff --git a/third_party/wayland/features.gni b/third_party/wayland/features.gni
index 424be6e75be0e0..48f5f70531d2a8 100644
--- a/third_party/wayland/features.gni
+++ b/third_party/wayland/features.gni
@@ -9,7 +9,7 @@ import("//build/config/sanitizers/sanitizers.gni")
 declare_args() {
   # Controls whether the build should use the version of Wayland
   # library shipped with the system or Chromium third_party.
-  use_system_libwayland = is_linux && !is_chromecast && !is_chromeos_lacros &&
+  use_system_libwayland = is_linux && !is_castos &&
                           default_toolchain != "//build/toolchain/cros:target"
 
   # Path to wayland-scanner. Has effect only when the system libwayland is used.
diff --git a/third_party/webrtc_overrides/BUILD.gn b/third_party/webrtc_overrides/BUILD.gn
index 933a908d5ccc43..5862bfd7287bfa 100644
--- a/third_party/webrtc_overrides/BUILD.gn
+++ b/third_party/webrtc_overrides/BUILD.gn
@@ -117,7 +117,7 @@ webrtc_public_deps = [
 if (defined(rtc_exclude_system_time) && rtc_exclude_system_time) {
   webrtc_public_deps += [ ":system_time" ]
 }
-if (is_chromecast) {
+if (is_castos || is_cast_android) {
   webrtc_public_deps += [
     "//third_party/webrtc/api:network_state_predictor_api",
     "//third_party/webrtc/api/audio:audio_frame_api",
@@ -132,7 +132,7 @@ if (is_chromecast) {
     "//third_party/webrtc/modules/video_coding:codec_globals_headers",
   ]
 }
-if (is_chromecast || is_nacl) {
+if (is_castos || is_cast_android || is_nacl) {
   # For chromecast and NaCL, provide a default field trial implementation.
   webrtc_public_deps += [ "//third_party/webrtc/system_wrappers:field_trial" ]
 } else {