Integrate WebUSB with Feature Policy

third_party/WebKit/Source/platform/feature_policy/FeaturePolicy.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/feature_policy/FeaturePolicy.h"
 
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/json/JSONValues.h"
 #include "platform/network/HTTPParsers.h"
 #include "platform/weborigin/SecurityOrigin.h"
@@ skipping 116 matching lines @@
 
   return whitelists;
 }
 
 const FeatureNameMap& GetDefaultFeatureNameMap() {
   DEFINE_STATIC_LOCAL(FeatureNameMap, default_feature_name_map, ());
   if (default_feature_name_map.IsEmpty()) {
     default_feature_name_map.Set("fullscreen",
                                  WebFeaturePolicyFeature::kFullscreen);
     default_feature_name_map.Set("payment", WebFeaturePolicyFeature::kPayment);
+    default_feature_name_map.Set("usb", WebFeaturePolicyFeature::kUsb);

[iclelland.google, 2017/05/02 14:42:52]

Can you make this line conditional on RuntimeEnabledFeatures::WebUSB? WebUSB
implies FP, but not the other way around, and we shouldn't be recognizing the
feature in policy declarations if WebUSB is disabled in the browser.

[Reilly Grant (use Gerrit), 2017/05/02 19:29:05]

WebUSB is an Origin Trial so RuntimeEnabledFeature::webUSBEnabled() may return
false even if the API is exposed to the web. It's confusing but that's what
we're stuck with.

[iclelland, 2017/05/04 15:24:08]

Right, of course. (And other than plumbing the execution context down to this
method, that's probably not going to change soon.) I was thinking that this was
part of shipping WebUSB, and removing it from origin trials.

     if (RuntimeEnabledFeatures::featurePolicyExperimentalFeaturesEnabled()) {
       default_feature_name_map.Set("vibrate",
                                    WebFeaturePolicyFeature::kVibrate);
       default_feature_name_map.Set("camera", WebFeaturePolicyFeature::kCamera);
       default_feature_name_map.Set("encrypted-media",
                                    WebFeaturePolicyFeature::kEme);
       default_feature_name_map.Set("microphone",
                                    WebFeaturePolicyFeature::kMicrophone);
       default_feature_name_map.Set("speaker",
                                    WebFeaturePolicyFeature::kSpeaker);
@@ skipping 14 matching lines @@
                                    WebFeaturePolicyFeature::kSyncScript);
       default_feature_name_map.Set("sync-xhr",
                                    WebFeaturePolicyFeature::kSyncXHR);
       default_feature_name_map.Set("webrtc", WebFeaturePolicyFeature::kWebRTC);
     }
   }
   return default_feature_name_map;
 }
 
 }  // namespace blink