Another shard for content_browsertests

The typical run time for these tests is regularly at or over the
execution limit on "Linux ASan Tests (sandboxed)". Adding a shard.

Bug: 955853
Change-Id: Ie81cdf1eccbee827b134c2820a51bd7f263243e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1580442
Commit-Queue: Chrome Cunningham <[email protected]>
Auto-Submit: Chrome Cunningham <[email protected]>
Reviewed-by: John Budorick <[email protected]>
Cr-Commit-Position: refs/heads/master@{#653463}
diff --git a/testing/buildbot/test_suite_exceptions.pyl b/testing/buildbot/test_suite_exceptions.pyl
index f1a5e08..ec81eee 100644
--- a/testing/buildbot/test_suite_exceptions.pyl
+++ b/testing/buildbot/test_suite_exceptions.pyl
@@ -421,6 +421,11 @@
           '--disable-features=WebRTC-H264WithOpenH264FFmpeg',
         ],
       },
+      'Linux ASan Tests (sandboxed)': {
+        'swarming': {
+          'shards': 2, # https://crbug.com/955853
+        },
+      },
     },
   },
   'content_shell_crash_test': {