The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9a05ae84e268e91f39a684bc565484110c16da1b

commit 9a05ae84e268e91f39a684bc565484110c16da1b
Author: reillyg <reillyg@chromium.org>
Date: Wed Feb 22 23:05:19 2017

Make the navigator.usb attribute accessible only in secure contexts.

Instead of performing secure context checks inside every method of the
USB object this change removes it from the Navigator object when not in
a secure context. This is equivalent to adding the [SecureContext]
extended attribute to the NavigatorUSB interface but the WebIDL code
generator doesn't support mixing it with [OriginTrialEnabled]. Instead
the secure context check is added to the hand-written Origin Trial code
in ConditionalFeaturesForModules.cpp.

BUG= 691031 

Review-Url: https://codereview.chromium.org/2698083008
Cr-Commit-Position: refs/heads/master@{#452256}

[add] https://crrev.com/9a05ae84e268e91f39a684bc565484110c16da1b/third_party/WebKit/LayoutTests/http/tests/usb/insecure-context.html
[add] https://crrev.com/9a05ae84e268e91f39a684bc565484110c16da1b/third_party/WebKit/LayoutTests/http/tests/usb/secure-context.html
[modify] https://crrev.com/9a05ae84e268e91f39a684bc565484110c16da1b/third_party/WebKit/Source/bindings/modules/v8/ConditionalFeaturesForModules.cpp
[modify] https://crrev.com/9a05ae84e268e91f39a684bc565484110c16da1b/third_party/WebKit/Source/modules/webusb/NavigatorUSB.idl
[modify] https://crrev.com/9a05ae84e268e91f39a684bc565484110c16da1b/third_party/WebKit/Source/modules/webusb/USB.cpp