Kokoro: Use depot_tools in docker image

This has now been added.

Bug: tint:652
Change-Id: I5ed8a825dcca500748d5ced66f1ce41dd0c9d6b8
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/45344
Auto-Submit: Ben Clayton <bclayton@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>

kokoro/linux/docker.sh

@@ -39,9 +39,11 @@ function status {
     task_begin $@
 }
 
+ORIGINAL_SRC_DIR="$(pwd)"
+
 . /bin/using.sh # Declare the bash `using` function for configuring toolchains.
 
-ORIGINAL_SRC_DIR="$(pwd)"
+using depot_tools
 
 status "Cloning to clean source directory"
 # We do this so that the docker script can be tested in a local development
@@ -51,14 +53,6 @@ mkdir -p ${SRC_DIR}
 cd ${SRC_DIR}
 git clone ${ORIGINAL_SRC_DIR} .
 
-status "Fetching depot_tools"
-# TODO(bclayton): Add depot_tools to the docker image
-mkdir -p /tmp/depot_tools
-curl https://storage.googleapis.com/chrome-infra/depot_tools.zip -o /tmp/depot_tools.zip
-unzip /tmp/depot_tools.zip -d /tmp/depot_tools
-rm /tmp/depot_tools.zip
-export PATH="/tmp/depot_tools:$PATH"
-
 status "Fetching dependencies"
 cp standalone.gclient .gclient
 gclient sync