Fix the clipboard feature spec.

BUG=460610

Review-Url: https://codereview.chromium.org/2163883006
Cr-Commit-Position: refs/heads/master@{#406724}

extensions/common/api/_api_features.json

@@ -150,14 +150,10 @@
     "dependencies": ["manifest:bluetooth"],
     "contexts": ["blessed_extension"]
   },
-  "clipboard": [{
+  "clipboard": {
     "dependencies": ["permission:clipboard", "permission:clipboardRead"],
-    "contexts": ["blessed_extension"],
-    "platforms": ["chromeos"]
-  }, {
-    "channel": "dev",
-    "extension_types": ["platform_app"]
-  }],  
+    "contexts": ["blessed_extension"]       
+  },
   "declarativeWebRequest": {
     "dependencies": ["permission:declarativeWebRequest"],
     "contexts": ["blessed_extension"]

extensions/common/api/_permission_features.json

@@ -171,7 +171,8 @@
   },
   "clipboard": {
     "channel": "dev",
-    "extension_types": ["platform_app"]
+    "extension_types": ["platform_app"],
+    "platforms": ["chromeos"]
   },
   "declarativeWebRequest": {
       "channel": "beta",