Add a helper script to expose which version of adb the android scripts use.

platform_tools/android/bin/adb_print_path

Index: platform_tools/android/bin/adb_print_path
diff --git a/platform_tools/android/bin/adb_print_path b/platform_tools/android/bin/adb_print_path
new file mode 100755
index 0000000000000000000000000000000000000000..4067f04c0e8a7f0388a1acdef4c4fdb1d6785337
--- /dev/null
+++ b/platform_tools/android/bin/adb_print_path
@@ -0,0 +1,12 @@
+#!/bin/bash
+#
+# adb_print_path: prints the path to the copy of adb that will be used by Skia's
+# android scripts. This is used by Skia's build infrastructure to ensure that
+# we use the same adb revision (and instance). 
+
+SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+source $SCRIPT_DIR/android_setup.sh
+source $SCRIPT_DIR/utils/setup_adb.sh
+
+echo $ADB
+exit 0