Fix channel check for fatal error suppression.

extensions/common/extension_api.cc

Index: extensions/common/extension_api.cc
diff --git a/extensions/common/extension_api.cc b/extensions/common/extension_api.cc
index 9e284f245feca16c872420bd53387c8d9c07ca92..698e159218d5fe46b065d220fe7c1b0d48352829 100644
--- a/extensions/common/extension_api.cc
+++ b/extensions/common/extension_api.cc
@@ -267,7 +267,10 @@ Feature::Availability ExtensionAPI::IsAvailable(const std::string& full_name,
                                                 Feature::Context context,
                                                 const GURL& url) {
   Feature* feature = GetFeatureDependency(full_name);
-  CHECK(feature) << full_name;
+  if (!feature) {
+    return Feature::CreateAvailability(Feature::NOT_PRESENT,
+        std::string("Unknown feature: ") + full_name);
+  }
   return IsAvailable(*feature, extension, context, url);
 }