UserAgent: Mozilla/5.0 (X11; CrOS x86_64 9000.82.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36
Platform: 9000.82.0 (Official Build) stable-channel chell

Example URL:
youtube.com

Steps to reproduce the problem:
1. Use usbC to HDMI adapter for presentation on external beamer/screen
2. Unplug the adapter and try to open youtube video
3. 

What is the expected behavior?
The sound plays from the chromebook internal speaker

What went wrong?
 While the youtube video with the sound is played there is no sound from the internal speaker. Also no sound if the headset is plugged in.
The fix is to plug back the usb-c to hdmi adapter, connect to external screen and then manually switch the audio input to internal speaker.

Did this work before? N/A 

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

Does this work in other browsers? Yes

Chrome version: 56.0.2924.87  Channel: stable
OS Version: 9000.82.0
Flash Version: 24.0.0.194 

Contents of chrome://gpu: 
Graphics Feature Status
Canvas: Hardware accelerated
Flash: Hardware accelerated
Flash Stage3D: Hardware accelerated
Flash Stage3D Baseline profile: Hardware accelerated
Compositing: Hardware accelerated
Multiple Raster Threads: Enabled
Native GpuMemoryBuffers: Software only. Hardware acceleration disabled
Panel Fitting: Unavailable
Rasterization: Software only. Hardware acceleration disabled
Video Decode: Hardware accelerated
Video Encode: Hardware accelerated
VPx Video Decode: Hardware accelerated
WebGL: Hardware accelerated
WebGL2: Hardware accelerated
Driver Bug Workarounds
clear_uniforms_before_first_program_use
count_all_in_varyings_packing
disable_discard_framebuffer
msaa_is_slow
scalarize_vec_and_mat_constructor_args
Problems Detected
Chrome OS panel fitting is only supported for Intel IVB and SNB Graphics Controllers
Disabled Features: panel_fitting
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
Accelerated rasterization has been disabled, either via blacklist, about:flags or the command line.
Disabled Features: rasterization
Native GpuMemoryBuffers have been disabled, either via about:flags or command line.
Disabled Features: native_gpu_memory_buffers
Version Information
Data exported	2/23/2017, 4:02:07 PM
Chrome version	Chrome/56.0.2924.87
Operating system	Linux 3.18.0-13527-gc2f2230
Software rendering list version	12.06
Driver bug list version	9.24
ANGLE commit id	a4aaa2de57dc
2D graphics backend	Skia/56 0
Command Line Args	--ppapi-flash-path=/opt/google/chrome/pepper/libpepflashplayer.so --ppapi-flash-version=24.0.0.194 --ui-prioritize-in-gpu-process --use-gl=egl --gpu-sandbox-failures-fatal=yes --arc-available --enable-logging --log-level=1 --use-cras --enable-wayland-server --user-data-dir=/home/chronos --max-unused-resource-memory-usage-percentage=5 --login-profile=user --has-chromeos-keyboard --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 --guest-wallpaper-large=/usr/share/chromeos-assets/wallpaper/guest_large.jpg --guest-wallpaper-small=/usr/share/chromeos-assets/wallpaper/guest_small.jpg --enable-prefixed-encrypted-media --enable-consumer-kiosk --enterprise-enrollment-initial-modulus=15 --enterprise-enrollment-modulus-limit=19 --vmodule=screen_locker=2,webui_screen_locker=2,lock_state_controller=2,webui_login_view=2,power_button_observer=2,*ui/display/chromeos*=1,*ash/display*=1,*ui/ozone*=1,*zygote*=1,*plugin*=2,auto_enrollment_controller=1,*chromeos/login/*=1,*arc/*=1 --login-manager --first-exec-after-boot
Driver Information
Initialization time	19
In-process GPU	false
Sandboxed	true
GPU0	VENDOR = 0x8086, DEVICE= 0x191e
Optimus	false
AMD switchable	false
Driver vendor	Mesa
Driver version	12.1.0
Driver date	
Pixel shader version	3.10
Vertex shader version	3.10
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 515 (Skylake GT2)
GL_VERSION	OpenGL ES 3.1 Mesa 12.1.0-devel (git-b010fa8)
GL_EXTENSIONS	GL_EXT_blend_minmax GL_EXT_multi_draw_arrays GL_EXT_texture_filter_anisotropic GL_EXT_texture_compression_dxt1 GL_EXT_texture_format_BGRA8888 GL_OES_compressed_ETC1_RGB8_texture GL_OES_depth24 GL_OES_element_index_uint GL_OES_fbo_render_mipmap GL_OES_mapbuffer GL_OES_rgb8_rgba8 GL_OES_standard_derivatives GL_OES_stencil8 GL_OES_texture_3D 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_EXT_texture_sRGB_decode GL_OES_EGL_image GL_OES_depth_texture GL_OES_packed_depth_stencil GL_EXT_texture_type_2_10_10_10_REV GL_OES_get_program_binary GL_APPLE_texture_max_level GL_EXT_discard_framebuffer GL_EXT_read_format_bgra GL_NV_fbo_color_attachments GL_OES_EGL_image_external GL_OES_EGL_sync GL_OES_vertex_array_object GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_EXT_texture_rg GL_EXT_unpack_subimage GL_NV_draw_buffers GL_NV_read_buffer GL_NV_read_depth GL_NV_read_depth_stencil GL_NV_read_stencil GL_EXT_draw_buffers GL_EXT_map_buffer_range GL_KHR_debug GL_KHR_robustness GL_KHR_texture_compression_astc_ldr GL_OES_depth_texture_cube_map GL_OES_surfaceless_context GL_EXT_color_buffer_float GL_EXT_separate_shader_objects GL_EXT_shader_integer_mix GL_EXT_copy_image GL_EXT_draw_buffers_indexed GL_EXT_draw_elements_base_vertex GL_EXT_gpu_shader5 GL_EXT_polygon_offset_clamp GL_EXT_shader_io_blocks GL_EXT_texture_border_clamp GL_EXT_texture_buffer GL_KHR_context_flush_control GL_KHR_robust_buffer_access_behavior GL_OES_copy_image GL_OES_draw_buffers_indexed GL_OES_draw_elements_base_vertex GL_OES_gpu_shader5 GL_OES_sample_shading GL_OES_sample_variables GL_OES_shader_io_blocks GL_OES_shader_multisample_interpolation GL_OES_texture_border_clamp GL_OES_texture_buffer GL_OES_texture_stencil8 GL_OES_texture_storage_multisample_2d_array GL_EXT_blend_func_extended GL_EXT_buffer_storage GL_EXT_shader_samples_identical GL_OES_shader_image_atomic GL_EXT_clip_cull_distance
Disabled Extensions	
Window system binding vendor	Mesa Project
Window system binding version	1.4 (DRI2)
Window system binding extensions	EGL_EXT_create_context_robustness EGL_EXT_image_dma_buf_import EGL_KHR_create_context EGL_KHR_fence_sync EGL_KHR_get_all_proc_addresses EGL_KHR_gl_renderbuffer_image EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_image_base EGL_KHR_reusable_sync EGL_KHR_surfaceless_context EGL_KHR_wait_sync EGL_MESA_configless_context EGL_MESA_drm_image EGL_MESA_image_dma_buf_export
Direct rendering	Yes
Reset notification strategy	0x0000
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	Software only
RG_88	Software only
BGR_565	GPU_READ
RGBA_4444	Software only
RGBX_8888	GPU_READ, SCANOUT
RGBA_8888	GPU_READ
BGRX_8888	GPU_READ, SCANOUT
BGRA_8888	GPU_READ
YVU_420	GPU_READ
YUV_420_BIPLANAR	Software only
UYVY_422	Software only
Log Messages
[1292:1298:0223/155404.306080:VERBOSE1:drm_device_manager.cc(54)] : Could not initialize DRM device for /sys/devices/platform/vgem/drm/card1
[1292:1298:0223/155404.990017:VERBOSE1:drm_display.cc(102)] : DRM configuring: device=/sys/devices/pci0000:00/0000:00:02.0/drm/card0 crtc=26 connector=36 origin=0,0 size=3200x1800
[1292:1298:0223/155450.607651:WARNING:screen_manager.cc(101)] : Display controller (crtc=26) already present.
[1292:1298:0223/155450.608631:VERBOSE1:drm_display.cc(102)] : DRM configuring: device=/sys/devices/pci0000:00/0000:00:02.0/drm/card0 crtc=26 connector=36 origin=0,0 size=3200x1800
[1292:1298:0223/155450.622051:VERBOSE1:drm_display.cc(102)] : DRM configuring: device=/sys/devices/pci0000:00/0000:00:02.0/drm/card0 crtc=30 connector=45 origin=0,1860 size=2560x1600
[1292:1298:0223/155554.396999:WARNING:screen_manager.cc(101)] : Display controller (crtc=26) already present.
[1292:1298:0223/155554.401128:VERBOSE1:drm_display.cc(102)] : DRM configuring: device=/sys/devices/pci0000:00/0000:00:02.0/drm/card0 crtc=26 connector=36 origin=0,0 size=3200x1800
[1292:1292:0223/155707.183818:ERROR:gles2_cmd_decoder.cc(9402)] : [.Offscreen-For-WebGL-0xe213fefd000]RENDER WARNING: there is no texture bound to the unit 0