telemetry: Add --browser-executable for 'exact'.

telemetry/telemetry/record_wpr_unittest.py

Index: telemetry/telemetry/record_wpr_unittest.py
diff --git a/telemetry/telemetry/record_wpr_unittest.py b/telemetry/telemetry/record_wpr_unittest.py
index 926dc8f88050c15f9f77ee211325234f25c30177..cce5c9ab9a91bebc00ebadeab7c6c91e88aa00d6 100644
--- a/telemetry/telemetry/record_wpr_unittest.py
+++ b/telemetry/telemetry/record_wpr_unittest.py
@@ -144,6 +144,8 @@ class RecordWprUnitTests(tab_test_case.TabTestCase):
     flags = ['--browser', self._browser.browser_type,
              '--remote', self._test_options.cros_remote,
              '--device', self._device]
+    if self._browser.browser_type == 'exact':
+      flags += ['--browser-executable', self._test_options.browser_executable]
     if self._test_options.chrome_root:
       flags += ['--chrome-root', self._test_options.chrome_root]
     return flags