[WebView] Fix the run_tests.sh script and add documentation.

android_webview/tools/system_webview_shell/test/data/run_tests.sh

Index: android_webview/tools/system_webview_shell/test/data/run_tests.sh
diff --git a/android_webview/tools/system_webview_shell/test/data/run_tests.sh b/android_webview/tools/system_webview_shell/test/data/run_tests.sh
deleted file mode 100755
index e017a505d6e8520b80eef314ce7109736bbe1bab..0000000000000000000000000000000000000000
--- a/android_webview/tools/system_webview_shell/test/data/run_tests.sh
+++ /dev/null
@@ -1,24 +0,0 @@
-#!/bin/bash
-
-# Copyright 2015 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-PACKAGE_NAME="org.chromium.webview_shell.test"
-DEVICE_WEBVIEW_TEST_PATH="/sdcard/chromium_tests_root/android_webview/tools/"
-DEVICE_WEBVIEW_TEST_PATH+="system_webview_shell/test/data/"
-TESTRUNNER="../../../../build/android/test_runner.py"
-
-$TESTRUNNER instrumentation \
-    --test-apk SystemWebViewShellLayoutTest \
-    -f 'WebViewLayoutTest*' \
-    --isolate-file-path android_webview/system_webview_shell_test_apk.isolate
-
-if [ "$1" = "rebaseline" ]; then
-  adb shell am instrument -w -e mode rebaseline -e class \
-      $PACKAGE_NAME.WebViewLayoutTest \
-      $PACKAGE_NAME/$PACKAGE_NAME.WebViewLayoutTestRunner
-  adb pull $DEVICE_WEBVIEW_TEST_PATH ../test_rebaseline/
-fi
-
-exit 0