Revert "Remove the WebVR Origin Trial."

This reverts commit 5c87a0a4.

Reason for revert: Re-enabling processing of WebVR Origin Trial tokens.

BUG=891425

Original change's description:
> Remove the WebVR Origin Trial.
>
> As previously announced (https://groups.google.com/a/chromium.org/d/msg/blink-dev/-s4pWwshKhI/M78h2_scBwAJ), the WebVR Origin Trial is ending after M68 as WebVR is replaced by the WebXR Device API and Origin Trial.
>
> WebVR can still be manually enabled through chrome://flags.
>
> BUG=758265
>
> Cq-Include-Trybots: luci.chromium.try:win_optional_gpu_tests_rel
> Change-Id: I752ac8d61c8436abd80a511cc66d4aad502d0245
> Reviewed-on: https://chromium-review.googlesource.com/1144278
> Reviewed-by: Daniel Cheng <dcheng@chromium.org>
> Reviewed-by: Brandon Jones <bajones@chromium.org>
> Reviewed-by: David Dorwin <ddorwin@chromium.org>
> Commit-Queue: Bill Orr <billorr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#576732}

TBR=ddorwin@chromium.org,dcheng@chromium.org,bajones@chromium.org,billorr@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 758265
Change-Id: Ic1be18fa173aa9a5ec90c3f5c8b388cc610c76d1
Cq-Include-Trybots: luci.chromium.try:win_optional_gpu_tests_rel
Reviewed-on: https://chromium-review.googlesource.com/c/1257670
Commit-Queue: Bill Orr <billorr@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Bill Orr <billorr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595977}

third_party/blink/renderer/modules/gamepad/gamepad.idl

@@ -43,7 +43,7 @@ interface Gamepad {
     // https://github.com/w3c/gamepad/pull/68
     [RuntimeEnabled=GamepadVibration, MeasureAs=GamepadVibrationActuator] readonly attribute GamepadHapticActuator? vibrationActuator;
 
-    [RuntimeEnabled=GamepadExtensions, MeasureAs=GamepadPose] readonly attribute GamepadPose? pose;
+    [OriginTrialEnabled=GamepadExtensions, MeasureAs=GamepadPose] readonly attribute GamepadPose? pose;
     [OriginTrialEnabled=WebXRGamepadSupport, MeasureAs=GamepadHand] readonly attribute GamepadHand hand;
 
     // https://w3c.github.io/webvr/#interface-gamepad

third_party/blink/renderer/modules/gamepad/gamepad_pose.idl

@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/gamepad/extensions.html#gamepadpose-interface
 [
-    RuntimeEnabled=GamepadExtensions
+    OriginTrialEnabled=GamepadExtensions
 ] interface GamepadPose {
     [MeasureAs=GamepadPoseHasOrientation] readonly attribute boolean hasOrientation;
     [MeasureAs=GamepadPoseHasPosition] readonly attribute boolean hasPosition;

third_party/blink/renderer/modules/gamepad/navigator_gamepad.cc

@@ -152,7 +152,7 @@ static void SampleGamepads(ListType* into,
       bool webxr_enabled =
           (context && OriginTrials::WebXRGamepadSupportEnabled(context) &&
            OriginTrials::WebXREnabled(context));
-      bool webvr_enabled = (context && RuntimeEnabledFeatures::WebVREnabled());
+      bool webvr_enabled = (context && OriginTrials::WebVREnabled(context));
 
       if (!webxr_enabled && !webvr_enabled) {
         // If neither WebXR nor WebVR are enabled, we should not expose XR-

third_party/blink/renderer/modules/modules_initializer.cc

@@ -239,7 +239,7 @@ void ModulesInitializer::OnClearWindowObjectInMainWorld(
   NavigatorGamepad::From(document);
   NavigatorServiceWorker::From(document);
   DOMWindowStorageController::From(document);
-  if (RuntimeEnabledFeatures::WebVREnabled())
+  if (OriginTrials::WebVREnabled(document.GetExecutionContext()))
     NavigatorVR::From(document);
   if (RuntimeEnabledFeatures::PresentationEnabled() &&
       settings.GetPresentationReceiver()) {

third_party/blink/renderer/modules/vr/navigator_vr.idl

@@ -10,5 +10,5 @@
     [SecureContext, OriginTrialEnabled=WebXR, MeasureAs=NavigatorXR] readonly attribute XR xr;
 
     // Legacy API
-    [RuntimeEnabled=WebVR, CallWith=ScriptState] Promise getVRDisplays();
+    [OriginTrialEnabled=WebVR, CallWith=ScriptState] Promise getVRDisplays();
 };

third_party/blink/renderer/modules/vr/vr_display.idl

@@ -10,7 +10,7 @@ enum VREye {
 // https://w3c.github.io/webvr/#interface-vrdisplay
 [
     ActiveScriptWrappable,
-    RuntimeEnabled=WebVR
+    OriginTrialEnabled=WebVR
 ] interface VRDisplay : EventTarget {
     // An identifier for this device unique across VRDisplays.
     readonly attribute unsigned long displayId;

third_party/blink/renderer/modules/vr/vr_display_capabilities.idl

@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webvr/#interface-vrdisplaycapabilities
 [
-    RuntimeEnabled=WebVR
+    OriginTrialEnabled=WebVR
 ] interface VRDisplayCapabilities {
   // Whether or not the VR display is capable of reporting user position.
   // If false position may still be reported using simulated values like

third_party/blink/renderer/modules/vr/vr_display_event.idl

@@ -12,7 +12,7 @@ enum VRDisplayEventReason {
 
 // https://w3c.github.io/webvr/#interface-vrdisplayevent
 [
-    RuntimeEnabled=WebVR,
+    OriginTrialEnabled=WebVR,
     Constructor(DOMString type, optional VRDisplayEventInit eventInitDict)
 ] interface VRDisplayEvent : Event {
     readonly attribute VRDisplay display;

third_party/blink/renderer/modules/vr/vr_eye_parameters.idl

@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webvr/#interface-vreyeparameters
 [
-    RuntimeEnabled=WebVR
+    OriginTrialEnabled=WebVR
 ] interface VREyeParameters {
   /* These values will vary after a FOV has been set */
   [DeprecateAs=VREyeParametersOffset] readonly attribute Float32Array offset;

third_party/blink/renderer/modules/vr/vr_frame_data.idl

@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webvr/#interface-vrframedata
 [
-    RuntimeEnabled=WebVR,
+    OriginTrialEnabled=WebVR,
     Constructor
 ] interface VRFrameData {
     readonly attribute Float32Array leftProjectionMatrix;

third_party/blink/renderer/modules/vr/vr_pose.idl

@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webvr/#interface-vrpose
 [
-    RuntimeEnabled=WebVR
+    OriginTrialEnabled=WebVR
 ] interface VRPose {
     readonly attribute Float32Array? position;
     [MeasureAs=VRPoseLinearVelocity] readonly attribute Float32Array? linearVelocity;

third_party/blink/renderer/modules/vr/vr_stage_parameters.idl

@@ -4,7 +4,7 @@
 
 // https://w3c.github.io/webvr/#interface-vrstageparameters
 [
-    RuntimeEnabled=WebVR
+    OriginTrialEnabled=WebVR
 ] interface VRStageParameters {
   // A 16 element array containing the components of a 4x4 transform
   // matrix.  This matrix transforms the sitting space position

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -538,6 +538,7 @@
     },
     {
       name: "GamepadExtensions",
+      origin_trial_feature_name: "WebVR1.1M62",
       status: "experimental",
     },
     {
@@ -1363,6 +1364,7 @@
     },
     {
       name: "WebVR",
+      origin_trial_feature_name: "WebVR1.1M62",
       status: "experimental",
     },
     {