This appears to be a driver-level out-of-memory error:

W : GLES-MALI OOM error: execution failed (gles_fb_context_flush at hardware/samsung_slsi/MaliT760_r7p0_Istor/product/gles/src/fb/mali_gles_fb_module_api.c:1496)

Unless there's evidence of a resource leak, I think there isn't really anything I can do here. Does the issue reproduce consistently if you start over fresh from a rebooted device? Do other WebVR pages have issues also?

Crash Report ID 166577ea4a861be1 :

0x0000007f90ab03c0	(libc.so + 0x000693c0 )	
0x0000007f90aadb50	(libc.so + 0x00066b50 )	
0x0000007f90a6a910	(libc.so + 0x00023910 )	
0x0000007f90a65240	(libc.so + 0x0001e240 )	
0x0000007f5c7ee514	(libchrome.so -debugger_posix.cc:228 )	base::debug::(anonymous namespace)::DebugBreak()
0x0000007f5c804894	(libchrome.so -logging.cc:846 )	logging::LogMessage::~LogMessage()
0x0000007f5d8fe7a4	(libchrome.so -compositor_impl_android.cc:766 )	content::CompositorImpl::OnGpuChannelEstablished(scoped_refptr<gpu::GpuChannelHost>)
0x0000007f5d413998	(libchrome.so -bind_internal.h:194 )	void base::internal::FunctorTraits<void (content::CompositorImpl::*)(scoped_refptr<gpu::GpuChannelHost>), void>::Invoke<base::WeakPtr<content::CompositorImpl> const&, scoped_refptr<gpu::GpuChannelHost> >(void (content::CompositorImpl::*)(scoped_refptr<gpu::GpuChannelHost>), base::WeakPtr<content::CompositorImpl> const&&&, scoped_refptr<gpu::GpuChannelHost>&&)
0x0000007f5d703424	(libchrome.so -callback.h:94 )	content::BrowserGpuChannelHostFactory::EstablishGpuChannel(base::RepeatingCallback<void (scoped_refptr<gpu::GpuChannelHost>)> const&)
0x0000007f5d8fe1f0	(libchrome.so -compositor_impl_android.cc:697 )	content::CompositorImpl::HandlePendingLayerTreeFrameSinkRequest()
0x0000007f5c7ef200	(libchrome.so -callback.h:65 )	base::debug::TaskAnnotator::RunTask(char const*, base::PendingTask*)
0x0000007f5c80bfac	(libchrome.so -message_loop.cc:394 )	base::MessageLoop::RunTask(base::PendingTask*)
0x0000007f5c80c3c0	(libchrome.so -message_loop.cc:406 )	base::MessageLoop::DoWork()
0x0000007f5c80ccb4	(libchrome.so -message_pump_android.cc:57 )	Java_org_chromium_base_SystemMessageHandler_nativeDoRunLoopOnce


1-10 10:46:34.811 26696 26711 E chromium: [ERROR:texture_manager.cc(3398)] [.Offscreen-For-WebGL-0x7f72075400]GL ERROR :GL_INVALID_OPERATION : glTexImage2D: <- error from previous GL command
11-10 10:46:34.821 26696 26711 E chromium: [ERROR:gles2_cmd_decoder.cc(6438)] [.Offscreen-For-WebGL-0x7f72075400]GL ERROR :GL_INVALID_OPERATION : glGenerateMipmap: <- error from previous GL command
[...]
11-10 10:46:38.381 26583 26583 I GVR : [vr/gvr/capi/src/HTTP://WEBADDRESS.ELIDED] Initialized GVR version 1.101.0
11-10 10:46:38.601 26583 27997 D mali_winsys: new_window_surface returns 0x3000, [2560x1440]-format:1
11-10 10:46:38.601 26583 27997 D : HTTP://WEBADDRESS.ELIDED isEnabled: 0
11-10 10:46:38.661 26583 26583 W ControllerServiceBridge: Bind failed. Service is not available.
11-10 10:46:38.661 26583 26583 E GVR : [vr/gvr/io/controller/controller_api_impl.cc:275] Controller service unavailable.
11-10 10:46:38.681 26696 26711 D mali_winsys: new_window_surface returns 0x3000, [2560x1344]-format:1
11-10 10:46:38.681 26696 26711 W : GLES-MALI OOM error: execution failed (gles_fb_context_flush at hardware/samsung_slsi/MaliT760_r7p0_Istor/product/gles/src/fb/mali_gles_fb_module_api.c:1496)
11-10 10:46:38.681 26696 26711 E libEGL : eglMakeCurrent:1056 error 3003 (EGL_BAD_ALLOC)
11-10 10:46:38.681 26696 26711 E chromium: [ERROR:gpu_command_buffer_stub.cc(770)] ContextResult::kFatalFailure: Failed to initialize virtual GL context.
11-10 10:46:38.681 26583 26583 F chromium: [FATAL:compositor_impl_android.cc(766)] Fatal error making Gpu context
11-10 10:46:38.681 26696 26711 E chromium: [ERROR:gles2_cmd_decoder.cc(16368)] Offscreen context lost via ARB/EXT_robustness. Reset status = GL_GUILTY_CONTEXT_RESET_KHR
11-10 10:46:38.681 26696 26711 E chromium: [ERROR:gles2_cmd_decoder.cc(4460)] GLES2DecoderImpl: Context reset detected after MakeCurrent.
11-10 10:46:38.681 26696 26711 E chromium: [ERROR:gpu_channel_manager.cc(200)] Exiting GPU process because some drivers cannot recover from problems.
11-10 10:46:38.681 26696 26711 E chromium: [ERROR:gpu_channel_manager.cc(200)] Exiting GPU process because some drivers cannot recover from problems.
11-10 10:46:38.771 26696 26711 I chromium: [INFO:child_process_service_impl.cc(70)] ChildProcessServiceImpl: Exiting child process.

This was previously reported as  issue 765690  and issue 730684. In both cases, it stopped reproing. Dup'ing to issue 730684. I'll reopen that one.