Turn on collection of Chrome crashes again.

When our autotest framework was switched to telemetry, the ability to
collect Chrome crashes was accidentally turned off. Turn it on again.

BUG=chromium:485379
TEST=Test that when Chrome crashes, crash dumps are included now.

Change-Id: Idef254515700f2bba81c7305030f21ed5eed8346
Reviewed-on: https://chromium-review.googlesource.com/269808
Reviewed-by: Albert Bodenhamer <abodenha@chromium.org>
Commit-Queue: David James <davidjames@chromium.org>
Trybot-Ready: David James <davidjames@chromium.org>
Tested-by: David James <davidjames@chromium.org>
diff --git a/client/common_lib/cros/chrome.py b/client/common_lib/cros/chrome.py
index cfcb9db..233941d 100644
--- a/client/common_lib/cros/chrome.py
+++ b/client/common_lib/cros/chrome.py
@@ -4,6 +4,7 @@
 
 import logging, os
 
+from autotest_lib.client.cros import constants
 from telemetry.core import browser_finder, browser_options, exceptions
 from telemetry.core import extension_to_load, util
 
@@ -95,6 +96,10 @@
         b_options.username = self.username
         b_options.password = self.password
 
+        # Turn on collection of Chrome coredumps via creation of a magic file.
+        # (Without this, Chrome coredumps are trashed.)
+        open(constants.CHROME_CORE_MAGIC_FILE, 'w').close()
+
         for i in range(num_tries):
             try:
                 browser_to_create = browser_finder.FindBrowser(finder_options)