media/chromeos: continue refactoring new VideoDecoder flags

crrev.com/c/2268540 and crrev.com/c/2268600 started changing the names
of the flag sent from ChromeOS command line builder to Chrome, namely
from:
 --force-disable-new-accelerated-video-decoder
to:
 --platform-disallows-chromeos-direct-video-decoder

Previous CLs essentially made both be set or not at the same time [1],
and this CL continues that refactoring chain by making Chrome aware of
the new name. The next CL will finally remove the "old" name.

This should have happened earlier but somehow I got sidetracked...

[1] https://source.chromium.org/chromiumos/chromiumos/codesearch/+/master:src/platform2/libchromeos-ui/chromeos/ui/chromium_command_builder.cc;l=534-537

Bug: b/159825227
Change-Id: I2a9a8527fc66c114ccad37197c5cfdad39e21f37
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2398905Reviewed-by: Andres Calderon Jaramillo <andrescj@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Auto-Submit: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807590}

chrome/browser/flag_descriptions.cc

@@ -3679,10 +3679,10 @@ const char kChromeOSDirectVideoDecoderName[] = "ChromeOS Direct Video Decoder";
 const char kChromeOSDirectVideoDecoderDescription[] =
     "Enables the hardware-accelerated ChromeOS direct media::VideoDecoder "
     "implementation. Note that this might be entirely disallowed by the "
-    "--force-disable-new-accelerated-video-decoder command line switch which "
-    "is added for platforms where said direct VideoDecoder does not work or is "
-    "not well tested (see the disable_cros_video_decoder USE flag in Chrome "
-    "OS)";
+    "--platform-disallows-chromeos-direct-video-decoder command line switch "
+    "which is added for platforms where said direct VideoDecoder does not work "
+    "or is not well tested (see the disable_cros_video_decoder USE flag in "
+    "Chrome OS)";
 #endif  // defined(OS_CHROMEOS) && BUILDFLAG(USE_CHROMEOS_MEDIA_ACCELERATION)
 
 const char kCdmFactoryDaemonName[] = "CDM Factory Daemon";

media/base/media_switches.cc

@@ -193,8 +193,7 @@ const char kEnableLiveCaptionPrefForTesting[] =
 // specific configurations that are signalled via this command line flag.
 // TODO(b/159825227): remove when the "old" video decoder is fully launched.
 const char kPlatformDisallowsChromeOSDirectVideoDecoder[] =
-    // TODO(mcasas): Rename the flag string when crrev.com/c/2268600 lands.
-    "force-disable-new-accelerated-video-decoder";
+    "platform-disallows-chromeos-direct-video-decoder";
 #endif
 
 namespace autoplay {