WebVR: add angular velocity estimate to pose

chrome/browser/android/vr_shell/vr_shell.h

Index: chrome/browser/android/vr_shell/vr_shell.h
diff --git a/chrome/browser/android/vr_shell/vr_shell.h b/chrome/browser/android/vr_shell/vr_shell.h
index 7a3de3000f39c4ee92d3cc28a4516f973d1463f3..ef9162610ef91aa428a3397e285f75cdcb71f87d 100644
--- a/chrome/browser/android/vr_shell/vr_shell.h
+++ b/chrome/browser/android/vr_shell/vr_shell.h
@@ -182,9 +182,22 @@ class VrShell : public device::GvrDelegate,
   void UpdateGamepadData(device::GvrGamepadData) override;
   void RegisterGamepadDataFetcher(device::GvrGamepadDataFetcher*) override;
 
-  // TODO(mthiesse): Find a better place for these functions to live.
-  static device::mojom::VRPosePtr VRPosePtrFromGvrPose(gvr::Mat4f head_mat);
+  // TODO(mthiesse): Find a better place for these functions to live. They are
+  // called from both vr_shell_gl and non_presenting_gvr_delegate.
+
+  // Creates a WebVR pose from a GVR pose, including filling in an angular
+  // velocity estimate based on the change between two predicted poses.
+  static device::mojom::VRPosePtr VRPosePtrFromGvrPose(
+      gvr::Mat4f head_matrix_predicted,
+      gvr::Mat4f head_matrix_for_angular_velocity,
+      int64_t epsilon_nanos);
+
+  // Provides a recommended render resolution for WebVR, this is passed on to
+  // the application as renderWidth/Height
   static gvr::Sizei GetRecommendedWebVrSize(gvr::GvrApi* gvr_api);
+
+  // Fill in the VRDisplayInfo based on recommended size and other headset
+  // parameters.
   static device::mojom::VRDisplayInfoPtr CreateVRDisplayInfo(
       gvr::GvrApi* gvr_api,
       gvr::Sizei recommended_size,