[chromedriver] Do not pass in minidump path if empty

When specify log-path, minidump path will be empty if specifying
file in current dir such as --log-path=file.log. In this case,
we don't have to pass in the minidump path option to driver as
that is mainly used on bot and it will be specified on bot.

Bug: 3437
Change-Id: Iacc53af30330bc2615499aa2667adb61fd460a43
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2163422Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Shengfa Lin <shengfa@google.com>
Cr-Commit-Position: refs/heads/master@{#762143}

chrome/test/chromedriver/test/run_py_tests.py

@@ -310,7 +310,7 @@ class ChromeDriverBaseTest(unittest.TestCase):
       server_url = _CHROMEDRIVER_SERVER_URL
 
     if (not _ANDROID_PACKAGE_KEY and 'debugger_address' not in kwargs and
-          '_MINIDUMP_PATH' in globals()):
+          '_MINIDUMP_PATH' in globals() and _MINIDUMP_PATH):
       # Environment required for minidump not supported on Android
       # minidumpPath will fail parsing if debugger_address is set
       if 'experimental_options' in kwargs: