complete overhaul of webtry work partition between jail and host

experimental/webtry/setup/continue_install_jail.sh

+#!/bin/bash
+
+# this script runs as root inside the chroot environment and updates the depot tools, go environment,
+# and skia source.
+
+umount /dev/shm
+mount /dev/shm
+
+SKIA_BUILD=/skia_build
+cd ${SKIA_BUILD}
+
+# Install depot_tools.
+if [ -d depot_tools ]; then
+  (cd depot_tools && git pull);
+else
+  git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git;
+fi
+export PATH=$PATH:${SKIA_BUILD}/depot_tools
+
+# Sometimes you need to test patches on the server, to do that uncomment
+# the following commented out lines and update the PATCH env variable to the
+# name of the codereview to use.
+
+# rm -rf skia
+
+# Checkout the skia code and dependencies.
+mkdir skia
+cd skia
+gclient config --name . https://skia.googlesource.com/skia.git
+gclient sync
+git checkout master
+
+# PATCH=issue196723021_100001.diff
+# rm $PATCH
+# wget https://codereview.chromium.org/download/$PATCH
+# git apply $PATCH
+
+SKIA_GYP_OUTPUT_DIR=${SKIA_BUILD}/skia/out GYP_GENERATORS=ninja ./gyp_skia -Dskia_gpu=0
+
+ninja -C ${SKIA_BUILD}/skia/out/Release skia_lib
+