media: Add Feature to control External Clear Key key system support

media/base/media_switches.cc

Index: media/base/media_switches.cc
diff --git a/media/base/media_switches.cc b/media/base/media_switches.cc
index 8c796e7fd0f34200f03c67f84907062c7c342cdc..ee24def9df22a3c47e36b0227eb5d84636814273 100644
--- a/media/base/media_switches.cc
+++ b/media/base/media_switches.cc
@@ -167,8 +167,15 @@ const base::Feature kResumeBackgroundVideo {
 // Use shared block-based buffering for media.
 const base::Feature kUseNewMediaCache{"use-new-media-cache",
                                       base::FEATURE_ENABLED_BY_DEFAULT};
+
 // Correct video colors based on output display?
 const base::Feature kVideoColorManagement{"video-color-management",
                                           base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Enables support for External Clear Key (ECK) key system for testing on
+// supported platforms. On platforms that do not support ECK, this feature has
+// no effect.
+const base::Feature kExternalClearKeyForTesting{
+    "external-clear-key-for-testing", base::FEATURE_DISABLED_BY_DEFAULT};
+
 }  // namespace media