Pause drawing webvr when the App button is pressed

chrome/browser/android/vr_shell/vr_browser_interface.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 CHROME_BROWSER_ANDROID_VR_SHELL_VR_BROWSER_INTERFACE_H_
+#define CHROME_BROWSER_ANDROID_VR_SHELL_VR_BROWSER_INTERFACE_H_
+
+#include <memory>
+
+#include "base/android/jni_weak_ref.h"
+#include "base/bind.h"
+#include "base/memory/weak_ptr.h"
+#include "base/time/time.h"
+#include "chrome/browser/android/vr_shell/ui_interface.h"
+#include "device/vr/android/gvr/gvr_gamepad_data_provider.h"
+#include "device/vr/vr_service.mojom.h"
+
+namespace blink {
+class WebInputEvent;
+}
+
+namespace vr_shell {
+
+// An interface for communication with Vr Browser.

[cjgrant, 2017/05/02 18:07:06]

Here you could actually say this is an interface to VrShell.

[ymalik, 2017/05/02 20:28:40]

That's not entirely true because for e.g. OnAppButtonPressed goes to
UiSceneManager which runs on the gl thread (which then post tasks to vr shell to
pause the web contents). Does that make sense?

+class VrBrowserInterface {
+ public:
+  virtual ~VrBrowserInterface() {}
+
+  // TODO(ymalik): Add comments for these functions.

[cjgrant, 2017/05/02 18:07:06]

It'd be better to have a single high-level comment (up with the class comment)
saying that these calls are proxies to methods on VrShell.  No point in
duplicating function descriptions IMO.

[ymalik, 2017/05/02 20:28:40]

That's fair.

+  virtual void ContentSurfaceChanged(jobject surface) {}
+  virtual void GvrDelegateReady() {}
+  virtual void UpdateGamepadData(device::GvrGamepadData) {}
+  virtual void AppButtonGesturePerformed(UiInterface::Direction direction) {}
+  virtual void AppButtonPressed() {}

[cjgrant, 2017/05/02 18:07:06]

See previous note about "Pressed"

[ymalik, 2017/05/02 20:28:40]

Done.

+  virtual void ProcessContentGesture(
+      std::unique_ptr<blink::WebInputEvent> event) {}
+  virtual void ForceExitVr() {}
+  virtual void RunVRDisplayInfoCallback(
+      const base::Callback<void(device::mojom::VRDisplayInfoPtr)>& callback,
+      device::mojom::VRDisplayInfoPtr* info) {}
+  virtual void OnContentPaused(bool enabled) {}
+};
+
+}  // namespace vr_shell
+
+#endif  // CHROME_BROWSER_ANDROID_VR_SHELL_VR_BROWSER_INTERFACE_H_