mojo VR interface simplified

device/vr/vr_service.mojom

Index: device/vr/vr_service.mojom
diff --git a/device/vr/vr_service.mojom b/device/vr/vr_service.mojom
index 5dbf7025641ca0edd5f616e0ca2ba6d4a4f03df3..e4b2805ea761717fd416785afb5342741361ff09 100644
--- a/device/vr/vr_service.mojom
+++ b/device/vr/vr_service.mojom
@@ -57,6 +57,11 @@ struct VRDisplay {
    VREyeParameters rightEye;
 };
 
+struct VRDisplayWithService {
+   VRDisplay? display;

[leonhsl(Using Gerrit), 2016/10/17 09:03:29]

Does it make sense when VRDisplay is null? For what scenario?

+   VRDeviceService? service;

[leonhsl(Using Gerrit), 2016/10/17 09:03:29]

Same question with above, what scenario for the null VRDeviceService?

[shaobo.yan, 2016/10/18 01:10:48]

The VRDisplay should not be nullptr but the VRDeviceService could be.

The display and service should not be nullptr. Since all of them are related to
an VRDevice object and the object has been checked not null. So it should not be
nullptr.

+};
+
 struct VRLayerBounds {
    float left;
    float top;
@@ -65,22 +70,26 @@ struct VRLayerBounds {
 };
 
 interface VRService {
-  SetClient(VRServiceClient client);
+  GetDisplays() => (array<VRDisplayWithService> displays);
+};
+
+interface VRDeviceService {

[leonhsl(Using Gerrit), 2016/10/17 09:03:29]

We should avoid such interface naming as XXXService, as it is not a real
service,, how about 'VRDevice'?

[shaobo.yan, 2016/10/18 01:10:48]

Oh, thx for the info ! We already have a class named VRDevice. This interface is
used by VRDisplay object to communicate with VRDevice object on blink side,
maybe VRDeviceClient could be a name.

[leonhsl(Using Gerrit), 2016/10/18 07:12:10]

You could change 'module device' to 'module device.mojom', this way generated
class will live under a nested namespace device::mojom, to avoid name collision.
I think (VRDevice, VRDeviceClient) pair is appropriate naming practice to align
with other mojo interfaces inside Chromium.

+  RegisterDisplayService(VRDisplayService display_service);
 
-  GetDisplays() => (array<VRDisplay> displays);
   [Sync]
-  GetPose(uint32 index) => (VRPose? pose);
-  ResetPose(uint32 index);
+  GetPose() => (VRPose? pose);
+  ResetPose();
 
-  RequestPresent(uint32 index, bool secureOrigin) => (bool success);
-  ExitPresent(uint32 index);
-  SubmitFrame(uint32 index, VRPose? pose);
-  UpdateLayerBounds(uint32 index, VRLayerBounds leftBounds, VRLayerBounds rightBounds);
+  RequestPresent(bool secureOrigin) => (bool success);
+  ExitPresent();
+  SubmitFrame(VRPose? pose);
+  UpdateLayerBounds(VRLayerBounds leftBounds, VRLayerBounds rightBounds);
 };
 
-interface VRServiceClient {
+//NOTE: this interface will be held by each VRDevice and VRDisplay pair.
+interface VRDisplayService {

[leonhsl(Using Gerrit), 2016/10/17 09:03:29]

Naming change: to 'VRDisplay' or 'VRDeviceClient'

[shaobo.yan, 2016/10/18 01:10:48]

This interface is used by VRDevice to inform event to VRDisplay on blink side.
I'll change it to VRDisplayClient.

   OnDisplayChanged(VRDisplay display);
-  OnExitPresent(uint32 index);
+  OnExitPresent();
   OnDisplayConnected(VRDisplay display);
-  OnDisplayDisconnected(uint32 index);
+  OnDisplayDisconnected();
 };