Re-land^2 WebVR compositor bypass via BrowserMain context + mailbox

device/vr/vr_service.mojom

 // Copyright 2015 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.
 
 module device.mojom;
 
 import "mojo/common/time.mojom";
+import "gpu/ipc/common/mailbox_holder.mojom";
+import "gpu/ipc/common/sync_token.mojom";
 
 // A field of view, given by 4 degrees describing the view from a center point.
 struct VRFieldOfView {
   float upDegrees;
   float downDegrees;
   float leftDegrees;
   float rightDegrees;
 };
 
 // A display's position, orientation, velocity, and acceleration state at the
 // given timestamp.
 struct VRPose {
   double timestamp;

[klausw, 2017/03/10 02:49:32]

Not my change, this is from rebase:

commit f4b1ca9d2d930fad5daaf6291a7a41c2eb141465
Author: shaobo.yan <shaobo.yan@intel.com>
Date:   Wed Mar 8 17:13:32 2017 -0800

    Update API to latest spec : Remove VRFrameData#timestamp
    According to latest WebVR Spec, there are several changes. Remove
VRFrameData#timestamp is one of them.

    BUG=697167
    
    Review-Url: https://codereview.chromium.org/2736593002

   array<float, 4>? orientation;
   array<float, 3>? position;
   array<float, 3>? angularVelocity;
   array<float, 3>? linearVelocity;
   array<float, 3>? angularAcceleration;
   array<float, 3>? linearAcceleration;
 };
 
 struct VRDisplayCapabilities {
   bool hasOrientation;
@@ skipping 47 matching lines @@
   SetClient(VRServiceClient client) => (uint32 numberOfConnectedDevices);
   // Inform the service that the page is listening for vrdisplayactivate events.
   SetListeningForActivate(bool listening);
 };
 
 interface VRServiceClient {
   OnDisplayConnected(VRDisplay display, VRDisplayClient& request,
                      VRDisplayInfo displayInfo);
 };
 
+interface VRSubmitFrameClient {
+  OnSubmitFrameTransferred();
+  OnSubmitFrameRendered();
+};
+
 interface VRDisplay {
   ResetPose();
 
-  RequestPresent(bool secureOrigin) => (bool success);
+  RequestPresent(bool secureOrigin, VRSubmitFrameClient client) => (bool success);
   ExitPresent();
-  SubmitFrame(VRPose? pose);
+  SubmitFrame(int16 frameId, gpu.mojom.MailboxHolder mailboxHolder);
   UpdateLayerBounds(int16 frameId, VRLayerBounds leftBounds,
-                    VRLayerBounds rightBounds);
+                    VRLayerBounds rightBounds, int16 sourceWidth,
+                    int16 sourceHeight);
   GetVRVSyncProvider(VRVSyncProvider& request);
 };
 
 interface VRVSyncProvider {
-  enum Status { SUCCESS, RETRY };
+  enum Status { SUCCESS, CLOSING };
 
   // The frameId maps a VSync to a frame arriving from the compositor. IDs will
   // be reused after the frame arrives from the compositor. Negative IDs imply
   // no mapping.
   GetVSync() => (VRPose? pose, mojo.common.mojom.TimeDelta time, int16 frameId,
                  Status status);
 };
 
 interface VRDisplayClient {
   OnChanged(VRDisplayInfo display);
   OnExitPresent();
   OnBlur();
   OnFocus();
   OnActivate(VRDisplayEventReason reason);
   OnDeactivate(VRDisplayEventReason reason);
 };