[WPT sync] Add pinned depot_tools in checkout to PATH

This change appends the pinned depot_tools in Chromium checkout (at
//src/third_party/depot_tools) to PATH so that the wpt_{import,export}
scripts always work as long as we have a `gclient sync`ed checkout.

The main reason for the change is to fix the scripts on LUCI, where
depot_tools is no longer in PATH by default.

Bug: 803111
Change-Id: I9242befa3dbc9e735ae3a618dcd5b8f5eff5579d
Reviewed-on: https://chromium-review.googlesource.com/1252532Reviewed-by: Quinten Yearsley <qyearsley@chromium.org>
Commit-Queue: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595457}

third_party/blink/tools/blinkpy/common/path_finder.py

@@ -50,6 +50,12 @@ def add_blinkpy_thirdparty_dir_to_sys_path():
         sys.path.append(path)
 
 
+def add_depot_tools_dir_to_os_path():
+    path = get_depot_tools_dir()
+    if path not in os.environ['PATH']:
+        os.environ['PATH'] += os.pathsep + path
+
+
 def get_bindings_scripts_dir():
     return os.path.join(get_source_dir(), 'bindings', 'scripts')
 
@@ -62,6 +68,10 @@ def get_chromium_src_dir():
     return os.path.dirname(os.path.dirname(get_blink_dir()))
 
 
+def get_depot_tools_dir():
+    return os.path.join(get_chromium_src_dir(), 'third_party', 'depot_tools')
+
+
 def get_source_dir():
     return os.path.join(get_chromium_src_dir(), 'third_party', 'blink', 'renderer')
 

third_party/blink/tools/wpt_export.py

@@ -5,15 +5,14 @@
 
 """Pushes changes to web-platform-tests inside Chromium to the upstream repo."""
 
-import os
-import sys
-
 from blinkpy.common import exit_codes
 from blinkpy.common.host import Host
+from blinkpy.common.path_finder import add_depot_tools_dir_to_os_path
 from blinkpy.w3c.test_exporter import TestExporter
 
 
 def main():
+    add_depot_tools_dir_to_os_path()
     host = Host()
     exporter = TestExporter(host)
     try:

third_party/blink/tools/wpt_import.py

@@ -5,15 +5,14 @@
 
 """Pulls the latest revisions of the web-platform-tests."""
 
-import os
-import sys
-
 from blinkpy.common import exit_codes
 from blinkpy.common.host import Host
+from blinkpy.common.path_finder import add_depot_tools_dir_to_os_path
 from blinkpy.w3c.test_importer import TestImporter
 
 
 def main():
+    add_depot_tools_dir_to_os_path()
     host = Host()
     importer = TestImporter(host)
     try: