Switch default swarming pool name in mb & run-swarmed to chromium.tests.

Bug: 1011474
Change-Id: Ia35fbae4f6cf33052df6b0b1932ef641606caa25
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1908719Reviewed-by: Aaron Gable <agable@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714319}

tools/mb/mb.py

@@ -601,7 +601,7 @@ class MetaBuildWrapper(object):
     else:
       raise MBErr('unrecognized platform string "%s"' % self.platform)
 
-    return [('pool', 'Chrome'),
+    return [('pool', 'chromium.tests'),
             ('cpu', 'x86-64'),
             os_dim]
 

tools/run-swarmed.py

@@ -134,7 +134,7 @@ def main():
                       help='Number of copies to spawn.')
   parser.add_argument('--device-os', default='M',
                       help='Run tests on the given version of Android.')
-  parser.add_argument('--pool', default='Chrome',
+  parser.add_argument('--pool', default='chromium.tests',
                       help='Use the given swarming pool.')
   parser.add_argument('--results', '-r', default='results',
                       help='Directory in which to store results.')