Add travis CI config

This will let us setup travis-ci on the Breakpad GitHub mirror.

R=vapier@chromium.org, mark@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1873133003 .

scripts/travis-checkout.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+set -ex
+
+get_depot_tools() {
+  cd
+  git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
+  PATH="$HOME/depot_tools:$PATH"
+}
+
+gclient_sync() {
+  # Rename the source dir to match what gclient expects.
+  srcdir=$(basename "$TRAVIS_BUILD_DIR")
+  cd "${TRAVIS_BUILD_DIR}"/..
+  mv "${srcdir}" src
+  gclient config --unmanaged https://github.com/google/breakpad.git
+  gclient sync
+}
+
+main() {
+  get_depot_tools
+  gclient_sync
+}
+
+main "$@"