content: Port content_shell_crash_service target to GN build.

This is necessary because it is one of the dependencies of the
'blink_tests' group that should be built.

BUG=483171
R=avi@chromium.org,dpranke@chromium.org

CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:android_chromium_gn_compile_dbg,android_chromium_gn_compile_rel;tryserver.chromium.win:win8_chromium_gn_rel,win8_chromium_gn_dbg;tryserver.chromium.mac:mac_chromium_gn_rel,mac_chromium_gn_dbg

Review URL: https://codereview.chromium.org/1138653004

Cr-Commit-Position: refs/heads/master@{#330164}

• BUILD.gn[diff]
• content/content_shell.gypi[diff]
• content/shell/BUILD.gn[diff]