Fix third_party/blink/tools/debug_renderer PID finding.

Previously the shell redirection only redirected stdout, but the message was
being printed to stderr. While here, use trap to ensure that the output file
is removed even when bash exits abnormally.

Change-Id: Icf9f9de24bf115713b61e860616a6457be8fa593
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1945925
Auto-Submit: Jeremy Roman <jbroman@chromium.org>
Reviewed-by: Robert Flack <flackr@chromium.org>
Reviewed-by: Robert Ma <robertma@chromium.org>
Commit-Queue: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721181}

third_party/blink/tools/debug_renderer

@@ -42,8 +42,9 @@ if [ -z "$DEBUGGER" ]; then
 fi
 
 OUTPUT=$(mktemp "${TMPDIR:-/tmp}"/"$(basename $0)".XXXXX)
+trap "rm $OUTPUT" EXIT
 echo "$TARGET" ${TARGET_FLAGS[@]} >&2
-"$TARGET" ${TARGET_FLAGS[@]} 2>&1 > >(tee $OUTPUT) &
+"$TARGET" ${TARGET_FLAGS[@]} > >(tee $OUTPUT) 2>&1 &
 BROWSER_PID=$!
 
 wait_renderer_pid() {
@@ -66,4 +67,3 @@ if [ -n "$RENDERER_PID" ]; then
 fi
 
 wait
-rm $OUTPUT