Add deprecation messages for EME requestMediaKeySystemAccess features

third_party/WebKit/Source/core/frame/Deprecation.cpp

Index: third_party/WebKit/Source/core/frame/Deprecation.cpp
diff --git a/third_party/WebKit/Source/core/frame/Deprecation.cpp b/third_party/WebKit/Source/core/frame/Deprecation.cpp
index acd4a1ec5ee6789e01a315f9a3e05770479d27ef..2e8b2df69db80db5ce5ca59a2767c5a912acef29 100644
--- a/third_party/WebKit/Source/core/frame/Deprecation.cpp
+++ b/third_party/WebKit/Source/core/frame/Deprecation.cpp
@@ -390,6 +390,14 @@ String Deprecation::deprecationMessage(UseCounter::Feature feature) {
           "Please specify the desired codec(s) as part of the contentType.",
           milestoneString(M58));
 
+    case UseCounter::EncryptedMediaCapabilityNotProvided:
+      return String::format(
+          "EME requires that one of 'audioCapabilities' and "
+          "'videoCapabilities' must be non-empty. Non-standard support for "
+          "this will be removed in %s. Please specify at least one valid "
+          "capability for 'audioCapabilities' or 'videoCapabilities'.",
+          milestoneString(M58));
+
     case UseCounter::VRDeprecatedFieldOfView:
       return replacedBy("VREyeParameters.fieldOfView",
                         "projection matrices provided by VRFrameData");