WebVR: match GVR renderbuffer resolution to canvas resolution

chrome/browser/android/vr_shell/vr_shell_gl.h

Index: chrome/browser/android/vr_shell/vr_shell_gl.h
diff --git a/chrome/browser/android/vr_shell/vr_shell_gl.h b/chrome/browser/android/vr_shell/vr_shell_gl.h
index b04cb8a071418c2e3214013f536ec6c3467f5bdc..af121a2f9fb761160204f2140ef1d5a961348dc8 100644
--- a/chrome/browser/android/vr_shell/vr_shell_gl.h
+++ b/chrome/browser/android/vr_shell/vr_shell_gl.h
@@ -160,6 +160,8 @@ class VrShellGl : public device::mojom::VRVSyncProvider {
   // Current sizes for the render buffers.
   gvr::Sizei render_size_primary_;
   gvr::Sizei render_size_headlocked_;
+  gvr::Sizei render_size_primary_vrshell_ = {0, 0};
+  gvr::Sizei render_size_primary_webvr_ = {0, 0};
 
   std::unique_ptr<VrShellRenderer> vr_shell_renderer_;