Add optional --yes argument to tools/install_dependencies.sh.

This helps build automation.

Bug: skia:11124
Change-Id: I529f525845fb151861afc19651cdedcc0baa075d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/348196
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Joe Gregorio <jcgregorio@google.com>

tools/install_dependencies.sh

@@ -8,6 +8,9 @@
 # dependencies using your system's package manager.  If your system is
 # not supported, add logic here to support it.
 
+# Pass in --yes as the first argument to force apt-get to skip Y/n prompts while
+# being backward compatible with the old behavior.
+
 set -e
 
 # Return 0 iff all package name arguments are installed.
@@ -43,7 +46,7 @@ if command -v lsb_release > /dev/null ; then
                PACKAGES="${PACKAGES} ninja-build"
            fi
            if ! dpkg_all_installed $PACKAGES; then
-               sudo apt-get install $PACKAGES
+               sudo apt-get $1 install $PACKAGES
            fi
            exit
            ;;