[ChromeDriver] Fix path for old Chromium snapshots

Chromium snapshots before revision 579575 are still archived using
the old directory name.

TBR=crouleau@chromium.org

Change-Id: I4cc1e9ca51af9f8f21e22214af2110a6d8be8fe7
Reviewed-on: https://chromium-review.googlesource.com/1158709Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579802}

chrome/test/chromedriver/archive.py

@@ -70,15 +70,29 @@ def DownloadChrome(revision, dest_dir, site=Site.CHROMIUM_SNAPSHOT):
 
   zip_path = os.path.join(dest_dir, 'chrome-%s.zip' % revision)
   if not os.path.exists(zip_path):
-    url = site + '/%s/%s' % (_GetDownloadPlatform(), GetZipName(revision))
+    legacy = int(revision) < 579575
+    url = site + '/%s/%s' % (_GetDownloadPlatform(legacy), GetZipName(revision))
     print 'Downloading', url, '...'
     urllib.urlretrieve(url, zip_path)
   util.Unzip(zip_path, dest_dir)
   return os.path.join(dest_dir, GetDirName(), GetChromePathFromPackage())
 
 
-def _GetDownloadPlatform():
-  """Returns the name for this platform on the archive site."""
+def _GetDownloadPlatform(legacy=False):
+  """Returns the name for this platform on the archive site.
+
+  Args:
+    legacy: When True, return name used for builds before revision 579575.
+            TODO(johnchen@chromium.org): Remove when we stop supporting m69.
+  """
+  if legacy:
+    if util.IsWindows():
+      return 'Win'
+    elif util.IsMac():
+      return 'Mac'
+    elif util.IsLinux():
+      return 'Linux_x64'
+
   if util.IsWindows():
     return 'win32_rel'
   elif util.IsMac():