Allow VRDisplay to specify which frame the layer bounds should be updated at.

chrome/browser/android/vr_shell/vr_shell_gl.h

 // Copyright 2016 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_SHELL_GL_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_GL_H_
 
 #include <memory>
+#include <queue>
 
 #include "base/cancelable_callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
 #include "device/vr/android/gvr/gvr_delegate.h"
 #include "device/vr/vr_service.mojom.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "third_party/gvr-android-sdk/src/libraries/headers/vr/gvr/capi/include/gvr.h"
@@ skipping 53 matching lines @@
   void OnPause();
   void OnResume();
 
   void SetWebVrMode(bool enabled);
   void ContentBoundsChanged(int width, int height);
   void ContentPhysicalBoundsChanged(int width, int height);
   void UIBoundsChanged(int width, int height);
   void UIPhysicalBoundsChanged(int width, int height);
   base::WeakPtr<VrShellGl> GetWeakPtr();
 
-  void UpdateWebVRTextureBounds(const gvr::Rectf& left_bounds,
+  void UpdateWebVRTextureBounds(int16_t frame_index,
+                                const gvr::Rectf& left_bounds,
                                 const gvr::Rectf& right_bounds);
   gvr::GvrApi* gvr_api();
   void SetGvrPoseForWebVr(const gvr::Mat4f& pose, uint32_t pose_num);
   gvr::Sizei GetWebVRCompositorSurfaceSize();
 
   void UpdateScene(std::unique_ptr<base::ListValue> commands);
 
   void UpdateVSyncInterval(long timebase_nanos, double interval_seconds);
 
   void OnRequest(device::mojom::VRVSyncProviderRequest request);
@@ skipping 13 matching lines @@
   bool WebVrPoseByteIsValid(int pose_index_byte);
 
   void UpdateController(const gvr::Vec3f& forward_vector);
   void SendEventsToTarget(InputTarget input_target, int pixel_x,
                           int pixel_y);
   void SendGesture(InputTarget input_target,
                    std::unique_ptr<blink::WebInputEvent> event);
 
   void OnUIFrameAvailable();
   void OnContentFrameAvailable();
-  bool GetPixelEncodedPoseIndexByte(int* pose_index);
+  bool GetPixelEncodedFrameIndex(uint16_t* frame_index);
 
   void OnVSync();
 
   // VRVSyncProvider
   void GetVSync(const GetVSyncCallback& callback) override;
 
   void ForceExitVr();
 
-  device::mojom::VRPosePtr GetPose();
+  void SendVSync(base::TimeDelta time, const GetVSyncCallback& callback);
 
   // samplerExternalOES texture data for UI content image.
   int ui_texture_id_ = 0;
   // samplerExternalOES texture data for main content image.
   int content_texture_id_ = 0;
 
   std::unique_ptr<UiScene> scene_;
 
   scoped_refptr<gl::GLSurface> surface_;
   scoped_refptr<gl::GLContext> context_;
   scoped_refptr<gl::SurfaceTexture> ui_surface_texture_;
   scoped_refptr<gl::SurfaceTexture> content_surface_texture_;
 
   std::unique_ptr<gl::ScopedJavaSurface> ui_surface_;
   std::unique_ptr<gl::ScopedJavaSurface> content_surface_;
 
   std::unique_ptr<gvr::GvrApi> gvr_api_;
   std::unique_ptr<gvr::BufferViewportList> buffer_viewport_list_;
   std::unique_ptr<gvr::BufferViewport> buffer_viewport_;
   std::unique_ptr<gvr::BufferViewport> headlocked_left_viewport_;
   std::unique_ptr<gvr::BufferViewport> headlocked_right_viewport_;
   std::unique_ptr<gvr::BufferViewport> webvr_left_viewport_;
   std::unique_ptr<gvr::BufferViewport> webvr_right_viewport_;
   std::unique_ptr<gvr::SwapChain> swap_chain_;
+  typedef std::pair<gvr::Rectf, gvr::Rectf> BoundsPair;

[dcheng, 2017/01/27 09:41:33]

Nit: prefer using A = B over typedef B A;

[mthiesse, 2017/01/27 16:15:31]

Done.

+  std::queue<std::pair<uint8_t, BoundsPair>> pending_bounds_;
 
   // Current sizes for the render buffers.
   gvr::Sizei render_size_primary_;
   gvr::Sizei render_size_headlocked_;
 
   std::unique_ptr<VrShellRenderer> vr_shell_renderer_;
 
   bool touch_pending_ = false;
   gvr::Quatf controller_quat_;
 
   gvr::Vec3f target_point_;
   const ContentRectangle* target_element_ = nullptr;
   InputTarget current_input_target_ = InputTarget::NONE;
   int ui_tex_css_width_ = 0;
   int ui_tex_css_height_ = 0;
   int content_tex_css_width_ = 0;
   int content_tex_css_height_ = 0;
   gvr::Sizei content_tex_physical_size_ = {0, 0};
   gvr::Sizei ui_tex_physical_size_ = {0, 0};
 
-  // The pose ring buffer size must be a power of two to avoid glitches when
-  // the pose index wraps around. It should be large enough to handle the
-  // current backlog of poses which is 2-3 frames.
-  static constexpr int kPoseRingBufferSize = 8;
   std::vector<gvr::Mat4f> webvr_head_pose_;
   int webvr_texture_id_ = 0;
   bool web_vr_mode_;
   bool ready_to_draw_ = false;
   bool surfaceless_rendering_;
 
   std::unique_ptr<VrController> controller_;
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   base::CancelableClosure vsync_task_;
   base::TimeTicks vsync_timebase_;
   base::TimeDelta vsync_interval_;
 
   base::TimeDelta pending_time_;
   bool pending_vsync_ = false;
   GetVSyncCallback callback_;
   bool received_frame_ = false;
   mojo::Binding<device::mojom::VRVSyncProvider> binding_;
 
   base::WeakPtr<VrShell> weak_vr_shell_;
   base::WeakPtr<VrInputManager> content_input_manager_;
   base::WeakPtr<VrInputManager> ui_input_manager_;
   base::WeakPtr<VrShellDelegate> delegate_provider_;
   scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
 
-  uint32_t pose_index_ = 1;
-  int last_pose_ = 0;
+  uint8_t frame_index_ = 0;
+  // larger than frame_index_ so it can be initialized out-of-band.
+  uint16_t last_frame_index_ = -1;

[klausw (use chromium instead), 2017/01/19 01:34:27]

Initializing unsigned integers to negative numbers seems odd. Assuming it just
needs to be big enough to store a frame index and -1, just make it a signed
int16_t?

[mthiesse, 2017/01/26 23:23:03]

dcheng asked for all types to be unsigned, so we don't get a mismatch of signed
and unsigned. I tend to agree.

Initializing unsigned to -1 isn't very common, but it's not unheard of. See
https://cs.chromium.org/search/?q=uint.*%5C+%3D%5C+-1;&sq=package:chromium&ty...

[klausw, 2017/01/27 00:24:55]

How about UINT16_MAX from cstdint then? The -1 initialization seems like a
potential trap for someone doing a (last_frame_index >= 0) check somewhere,
though presumably the compiler would catch that.

[mthiesse, 2017/01/27 00:57:28]

So std::numeric_limits<decltype(last_frame_index_)>::max() is an option, but I
decided against it because it doesn't really convey the intent like -1 does. It
isn't really obvious that UINT16_MAX is impossible to reach after
initialization, especially when comparing against it in the cc file. -1 clearly
conveys that this is an uninitialized value that shouldn't be reached after
initialization.

Writing last_frame_index >= 0 for a uint type is just clearly a mistake in any
case, so we shouldn't worry about it.

 
   base::WeakPtrFactory<VrShellGl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(VrShellGl);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_GL_H_