Refactor GVR controller gamepad API integration

device/vr/android/gvr/gvr_gamepad_data_provider.h

+// Copyright 2017 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.
+
+#ifndef DEVICE_VR_ANDROID_GVR_GAMEPAD_DATA_PROVIDER_H
+#define DEVICE_VR_ANDROID_GVR_GAMEPAD_DATA_PROVIDER_H
+
+#include "third_party/gvr-android-sdk/src/libraries/headers/vr/gvr/capi/include/gvr_types.h"
+
+namespace device {
+
+class GvrGamepadDataFetcher;
+
+// Subset of GVR controller data needed for the gamepad API. Filled in
+// by vr_shell's VrController and consumed by GvrGamepadDataFetcher.
+struct GvrGamepadData {
+  int64_t timestamp;
+  gvr_vec2f touch_pos;
+  gvr_quatf orientation;
+  gvr_vec3f accel;
+  gvr_vec3f gyro;
+  bool is_touching;
+  bool controller_button_pressed;
+  bool right_handed;
+};
+
+// This class exposes GVR controller data to the gamepad API. Data is
+// polled by VrShellGl, then pushed from VrShell which implements the
+// GvrGamepadDataProvider interface.
+//
+// More specifically, here's the lifecycle, assuming VrShell
+// implements GvrGamepadDataProvider:
+//
+// - VrShell creates GvrGamepadDataFetcherFactory from
+//   VrShell::UpdateGamepadData.
+//
+// - GvrGamepadDataFetcherFactory creates GvrGamepadDataFetcher.
+//
+// - GvrGamepadDataFetcher registers itself with VrShell via
+//   VrShell::RegisterGamepadDataFetcher.
+//
+// - While presenting, VrShell::UpdateGamepadData calls
+//   GvrGamepadDataFetcher->SetGamepadData to push poses,
+//   GvrGamepadDataFetcher::GetGamepadData returns these when polled.
+//
+// - VrShell starts executing its destructor.
+//
+// - VrShell destructor unregisters GvrGamepadDataFetcherFactory.
+//
+// - GvrGamepadDataFetcherFactory destructor destroys GvrGamepadDataFetcher.
+//
+class GvrGamepadDataProvider {
+ public:
+  // Refresh current GVR controller data for use by gamepad API. The
+  // implementation also lazily creates and registers the GVR
+  // GamepadDataFetcherFactory with the GamepadDataFetcherManager as
+  // needed.
+  virtual void UpdateGamepadData(GvrGamepadData data) = 0;
+
+  // Called by the gamepad data fetcher constructor to register itself
+  // for receiving data via SetGamepadData. The fetcher must remain
+  // alive while the provider is calling SetGamepadData on it.
+  virtual void RegisterGamepadDataFetcher(GvrGamepadDataFetcher*) = 0;
+};
+
+}  // namespace device
+#endif  // DEVICE_VR_ANDROID_GVR_GAMEPAD_DATA_PROVIDER_H