I was only able to reproduce this on Windows. Repro steps:

D:\src\chromium\src>type out\Debug\args.gn
use_goma = true
goma_dir="c:\src\goma-win64"
is_debug = true
is_component_build = true
enable_nacl = false
target_cpu = "x86"
D:\src\chromium\src>ninja -C out\Debug content_shell
ninja: Entering directory `out\Debug'
ninja: no work to do.

D:\src\chromium\src>out\Debug\content_shell.exe --run-web-tests file\not\found

D:\src\chromium\src>#READY

DevTools listening on ws://127.0.0.1:57493/devtools/browser/43ba303a-be5d-4064-98b1-6320a03a1862
[25996:28084:1128/175056.489:ERROR:process_win.cc(167)] Unable to terminate process: Access is denied. (0x5)
[25996:45624:1128/175056.933:ERROR:bad_message.cc(27)] Terminating renderer for bad IPC message, reason 205
[25996:28084:1128/175056.984:ERROR:process_win.cc(167)] Unable to terminate process: Access is denied. (0x5)
[25996:9196:1128/175057.015:WARNING:discardable_shared_memory_manager.cc(410)] Some MojoDiscardableSharedMemoryManagerImpls are still alive. They will be leaked.
layer at (0,0) size 800x600
  LayoutView at (0,0) size 800x600
layer at (0,0) size 800x600
  LayoutBlockFlow {HTML} at (0,0) size 800x600
    LayoutBlockFlow {BODY} at (8,8) size 784x584
      LayoutText {#text} at (0,0) size 235x19
        text run at (0,0) width 235: "Could not load the requested resource."
      LayoutBR {BR} at (235,15) size 0x0
      LayoutText {#text} at (0,20) size 298x19
        text run at (0,20) width 298: "Error code: -6 (net::ERR_FILE_NOT_FOUND)"