UserAgent: Mozilla/5.0 (X11; CrOS x86_64 10575.58.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36
Platform: 10575.58.0 (Official Build) stable-channel eve

Example URL:
N/A - OS issue

Steps to reproduce the problem:
1. Plug in a secondary monitor (with no speakers) via USB-C port
2. Visit any site which outputs sound
3. Sound output is redirected to secondary monitor

What is the expected behavior?
I expected some intelligent behaviour whereby the secondary monitor is checked to see if sound output is present, and if not, sound continues to route to internal speakers. 

If that's not possible (i.e. sound capabilities are not reported by secondary monitor), then perhaps a pop-up on plugging in the monitor asking if user would like to redirect sound to the secondary monitor, with an option to default to this choice. 

The workaround (which took me some time to discover) is to click the time/battery icons at bottom right of screen, which brings up the menu which includes the volume slider - to the right end of that slider, an arrow appears, which in turn brings up the Audio Settings box, where audio output can be changed to the internal speakers.

Note that no option to route audio is available in Settings, with, or without, a secondary monitor plugged it (which is why it took me forever to figure this workaround out).

What went wrong?
All audio fails to output - it is routed to the secondary monitor (which in my case does not include any speakers) as soon as that secondary monitor is connected to the USB-C port. There is no indication to the user that has happened, and no option in Settings to re-route to the internal speakers.

Did this work before? No 

Is it a problem with Flash or HTML5? N/A

Does this work in other browsers? N/A

Chrome version: 67.0.3396.99  Channel: n/a
OS Version: 10575.58.0
Flash Version: 30.0.0.113

Contents of chrome://gpu: 

Graphics Feature Status
Canvas: Hardware accelerated
CheckerImaging: Disabled
Flash: Hardware accelerated
Flash Stage3D: Hardware accelerated
Flash Stage3D Baseline profile: Hardware accelerated
Compositing: Hardware accelerated
Multiple Raster Threads: Enabled
Native GpuMemoryBuffers: Hardware accelerated
Rasterization: Hardware accelerated
Surface Synchronization: Enabled
Video Decode: Hardware accelerated
Viz Service Display Compositor: Disabled
WebGL: Hardware accelerated
WebGL2: Hardware accelerated
Driver Bug Workarounds
clear_uniforms_before_first_program_use
count_all_in_varyings_packing
decode_encode_srgb_for_generatemipmap
disable_discard_framebuffer
msaa_is_slow
rely_on_implicit_sync_for_swap_buffers
scalarize_vec_and_mat_constructor_args
Problems Detected
Framebuffer discarding causes jumpy scrolling on Mali drivers: 301988
Applied Workarounds: disable_discard_framebuffer
Clear uniforms before first program use on all platforms: 124764, 349137
Applied Workarounds: clear_uniforms_before_first_program_use
Mesa drivers in ChromeOS handle varyings without static use incorrectly: 333885
Applied Workarounds: count_all_in_varyings_packing
Always rewrite vec/mat constructors to be consistent: 398694
Applied Workarounds: scalarize_vec_and_mat_constructor_args
On Intel GPUs MSAA performance is not acceptable for GPU rasterization: 527565
Applied Workarounds: msaa_is_slow
Disable KHR_blend_equation_advanced until cc shaders are updated: 661715
Applied Workarounds: disable(GL_KHR_blend_equation_advanced), disable(GL_KHR_blend_equation_advanced_coherent)
Decode and Encode before generateMipmap for srgb format textures on Chromeos Intel: 634519
Applied Workarounds: decode_encode_srgb_for_generatemipmap
Avoid waiting on a egl fence before pageflipping and rely on implicit sync.: 721463
Applied Workarounds: rely_on_implicit_sync_for_swap_buffers
Don't expose disjoint_timer_query extensions to WebGL: 808744
Viz service display compositor is not enabled by default.
Disabled Features: viz_display_compositor
Checker-imaging has been disabled via finch trial or the command line.
Disabled Features: checker_imaging
Version Information
Data exported	2018-08-20T00:24:33.197Z
Chrome version	Chrome/67.0.3396.99
Operating system	Linux 4.4.127-13890-g6c206f1711d4
Software rendering list URL	https://chromium.googlesource.com/chromium/src/+/a337fbf3c2ab8ebc6b64b0bfdce73a20e2e2252b/gpu/config/software_rendering_list.json
Driver bug list URL	https://chromium.googlesource.com/chromium/src/+/a337fbf3c2ab8ebc6b64b0bfdce73a20e2e2252b/gpu/config/gpu_driver_bug_list.json
ANGLE commit id	702006f4a07e
2D graphics backend	Skia/67 baf6686f92df805d3e25e80a0f3c79597cb3a6a5-
Command Line	/opt/google/chrome/chrome --ppapi-flash-path=/opt/google/chrome/pepper/libpepflashplayer.so --ppapi-flash-version=30.0.0.113 --ui-prioritize-in-gpu-process --use-gl=egl --enable-native-gpu-memory-buffers --enable-drm-atomic --enable-hardware-overlays=single-fullscreen,single-on-top --enable-webgl-image-chromium --enable-features=Pepper3DImageChromium,PointerEvent,EnableBackgroundBlur --gpu-sandbox-failures-fatal=yes --enable-logging --log-level=1 --use-cras --enable-wayland-server --user-data-dir=/home/chronos --force-clamshell-power-button --login-profile=user --has-chromeos-keyboard --enable-touchview --enable-voice-interaction --guest-wallpaper-large=/usr/share/chromeos-assets/wallpaper/guest_large.jpg --guest-wallpaper-small=/usr/share/chromeos-assets/wallpaper/guest_small.jpg --child-wallpaper-large=/usr/share/chromeos-assets/wallpaper/child_large.jpg --child-wallpaper-small=/usr/share/chromeos-assets/wallpaper/child_small.jpg --default-wallpaper-large=/usr/share/chromeos-assets/wallpaper/oem_large.jpg --default-wallpaper-small=/usr/share/chromeos-assets/wallpaper/oem_small.jpg --default-wallpaper-is-oem --arc-availability=officially-supported --enable-arc-oobe-optin --enterprise-enrollment-initial-modulus=15 --enterprise-enrollment-modulus-limit=19 --login-manager --policy-switches-begin --enable-password-generation --enable-features=enable-manual-password-generation --policy-switches-end --first-exec-after-boot --vmodule=arc_kiosk*=2,*arc/*=1,automatic_reboot_manager=1,tablet_power_button_controller=1,*chromeos/login/*=1,auto_enrollment_controller=1,*plugin*=2,*zygote*=1,*/ui/ozone/*=1,*/ui/display/manager/chromeos/*=1,*night_light*=1,power_button_observer=2,webui_login_view=2,lock_state_controller=2,webui_screen_locker=2,screen_locker=2 --enable-features=Pepper3DImageChromium,PointerEvent,EnableBackgroundBlur,enable-manual-password-generation
Driver Information
Initialization time	100
In-process GPU	false
Passthrough Command Decoder	false
Direct Composition	false
Supports overlays	false
Sandboxed	true
GPU0	VENDOR = 0x8086, DEVICE= 0x591e *ACTIVE*
Optimus	false
AMD switchable	false
Driver vendor	Mesa
Driver version	18.1.0
Driver date	
Pixel shader version	3.20
Vertex shader version	3.20
Max. MSAA samples	16
Machine model name	
Machine model version	
GL_VENDOR	Intel Open Source Technology Center
GL_RENDERER	Mesa DRI Intel(R) HD Graphics 615 (Kaby Lake GT2)
GL_VERSION	OpenGL ES 3.2 Mesa 18.1.0-devel (git-131e871385)
GL_EXTENSIONS	GL_ANDROID_extension_pack_es31a GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_APPLE_texture_max_level GL_EXT_blend_func_extended GL_EXT_blend_minmax GL_EXT_buffer_storage GL_EXT_clip_cull_distance GL_EXT_color_buffer_float GL_EXT_compressed_ETC1_RGB8_sub_texture GL_EXT_copy_image GL_EXT_discard_framebuffer GL_EXT_disjoint_timer_query GL_EXT_draw_buffers GL_EXT_draw_buffers_indexed GL_EXT_draw_elements_base_vertex GL_EXT_frag_depth GL_EXT_geometry_point_size GL_EXT_geometry_shader GL_EXT_gpu_shader5 GL_EXT_map_buffer_range GL_EXT_multi_draw_arrays GL_EXT_occlusion_query_boolean GL_EXT_polygon_offset_clamp GL_EXT_primitive_bounding_box GL_EXT_read_format_bgra GL_EXT_robustness GL_EXT_separate_shader_objects GL_EXT_shader_framebuffer_fetch GL_EXT_shader_integer_mix GL_EXT_shader_io_blocks GL_EXT_shader_samples_identical GL_EXT_tessellation_point_size GL_EXT_tessellation_shader GL_EXT_texture_border_clamp GL_EXT_texture_buffer GL_EXT_texture_compression_dxt1 GL_EXT_texture_cube_map_array GL_EXT_texture_filter_anisotropic GL_EXT_texture_format_BGRA8888 GL_EXT_texture_rg GL_EXT_texture_sRGB_decode GL_EXT_texture_type_2_10_10_10_REV GL_EXT_unpack_subimage GL_INTEL_conservative_rasterization GL_INTEL_performance_query GL_KHR_blend_equation_advanced GL_KHR_blend_equation_advanced_coherent GL_KHR_context_flush_control GL_KHR_debug GL_KHR_no_error GL_KHR_robust_buffer_access_behavior GL_KHR_robustness GL_KHR_texture_compression_astc_ldr GL_KHR_texture_compression_astc_sliced_3d GL_MESA_shader_integer_functions GL_NV_draw_buffers GL_NV_fbo_color_attachments GL_NV_image_formats GL_NV_read_buffer GL_NV_read_depth GL_NV_read_depth_stencil GL_NV_read_stencil GL_OES_EGL_image GL_OES_EGL_image_external GL_OES_EGL_sync GL_OES_compressed_ETC1_RGB8_texture GL_OES_copy_image GL_OES_depth24 GL_OES_depth_texture GL_OES_depth_texture_cube_map GL_OES_draw_buffers_indexed GL_OES_draw_elements_base_vertex GL_OES_element_index_uint GL_OES_fbo_render_mipmap GL_OES_geometry_point_size GL_OES_geometry_shader GL_OES_get_program_binary GL_OES_gpu_shader5 GL_OES_mapbuffer GL_OES_packed_depth_stencil GL_OES_primitive_bounding_box GL_OES_required_internalformat GL_OES_rgb8_rgba8 GL_OES_sample_shading GL_OES_sample_variables GL_OES_shader_image_atomic GL_OES_shader_io_blocks GL_OES_shader_multisample_interpolation GL_OES_standard_derivatives GL_OES_stencil8 GL_OES_surfaceless_context GL_OES_tessellation_point_size GL_OES_tessellation_shader GL_OES_texture_3D GL_OES_texture_border_clamp GL_OES_texture_buffer GL_OES_texture_cube_map_array GL_OES_texture_float GL_OES_texture_float_linear GL_OES_texture_half_float GL_OES_texture_half_float_linear GL_OES_texture_npot GL_OES_texture_stencil8 GL_OES_texture_storage_multisample_2d_array GL_OES_vertex_array_object GL_OES_vertex_half_float GL_OES_viewport_array
Disabled Extensions	GL_KHR_blend_equation_advanced GL_KHR_blend_equation_advanced_coherent
Disabled WebGL Extensions	EXT_disjoint_timer_query EXT_disjoint_timer_query_webgl2
Window system binding vendor	Mesa Project
Window system binding version	1.4 (DRI2)
Window system binding extensions	EGL_ANDROID_native_fence_sync EGL_EXT_create_context_robustness EGL_EXT_image_dma_buf_import EGL_EXT_image_dma_buf_import_modifiers EGL_KHR_config_attribs EGL_KHR_create_context EGL_KHR_create_context_no_error EGL_KHR_fence_sync EGL_KHR_get_all_proc_addresses EGL_KHR_gl_colorspace EGL_KHR_gl_renderbuffer_image EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_3D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_image_base EGL_KHR_no_config_context EGL_KHR_reusable_sync EGL_KHR_surfaceless_context EGL_EXT_pixel_format_float EGL_KHR_wait_sync EGL_MESA_configless_context EGL_MESA_drm_image EGL_MESA_image_dma_buf_export
Direct rendering	Yes
Reset notification strategy	0x8252
GPU process crash count	0
Compositor Information
Tile Update Mode	One-copy
Partial Raster	Enabled
GpuMemoryBuffers Status
ATC	Software only
ATCIA	Software only
DXT1	Software only
DXT5	Software only
ETC1	Software only
R_8	SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
R_16	Software only
RG_88	SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
BGR_565	GPU_READ
RGBA_4444	Software only
RGBX_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE
RGBA_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE
BGRX_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE
BGRX_1010102	Software only
RGBX_1010102	Software only
BGRA_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
RGBA_F16	Software only
YVU_420	GPU_READ
YUV_420_BIPLANAR	SCANOUT_CAMERA_READ_WRITE, SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
UYVY_422	Software only
Display(s) Information
Info	Display[21692109949126656] bounds=[0,0 2400x1600], workarea=[0,0 2400x1600], scale=1, internal.
Color space information	{primaries_d50_referred: [[0.6477, 0.3305], [0.3180, 0.6002], [0.1549, 0.0655]], transfer:0.0000*x + 0.0000 if x < 0.0000 else (1.0000*x + 0.0000)**2.2000 + 0.0000, matrix:RGB, range:FULL}
Bits per color component	8
Bits per pixel	24
Info	Display[1657447426027009] bounds=[2400,0 1080x1920], workarea=[2400,0 1080x1920], scale=1, external.
Color space information	{primaries:INVALID, transfer:INVALID, matrix:INVALID, range:INVALID}
Bits per color component	8
Bits per pixel	24
Video Acceleration Information
Decode h264 baseline	up to 4096x4096 pixels
Decode h264 main	up to 4096x4096 pixels
Decode h264 high	up to 4096x4096 pixels
Decode vp8	up to 4096x4096 pixels
Decode vp9 profile0	up to 4096x4096 pixels
Decode vp9 profile2	up to 4096x4096 pixels
Encode h264 baseline	up to 4096x4096 pixels and/or 30.000 fps
Encode h264 main	up to 4096x4096 pixels and/or 30.000 fps
Encode h264 high	up to 4096x4096 pixels and/or 30.000 fps
Encode vp9 profile0	up to 4096x4096 pixels and/or 30.000 fps

***HAVE SNIPPED OUT LOG FOR BREVITY (bug report says "comment too long" and won't let me submit) - HAPPY TO PROVIDE IF NEEDED

The secondary monitor I'm using is the AOC i1601fwux 16-inch IPS USB-C Powered Portable Monitor.

If sound is re-routed, the user should be notified. Also, options to manually route audio should appear in Settings, since that's the most obvious place for a user to go looking for audio options (the option in the bottom right volume slider is handy, and should remain - it's just not at all obvious (or wasn't to this user)).

Thank you.