Add large query mode to GPU unexpected pass finder

Adds --large-query-mode flag, which increases the effective max
--num-samples value for large test suites by using an initial, smaller
query to create a test filter which is used to reduce the amount of data
input into the ORDER BY clause in the actual query. This in turn allows
us to query more data before running into the hard memory limit when
using ORDER BY.

Additional includes several performance enhancements in order to try to
offset the additional runtime when using --large-query-mode.

Bug: 1175909
Change-Id: I49c35dca8011db2ea1a199d86876c0db89be54f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2718929
Auto-Submit: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#857796}

content/test/gpu/unexpected_pass_finder.py

@@ -122,6 +122,13 @@ def ParseArgs():
                       action='store_true',
                       default=False,
                       help='Disable logging for non-errors.')
+  parser.add_argument('--large-query-mode',
+                      action='store_true',
+                      default=False,
+                      help='Run the script in large query mode. This incurs '
+                      'a significant performance hit, but allows the use of '
+                      'larger sample sizes on large test suites by partially '
+                      'working around a hard memory limit in BigQuery.')
 
   args = parser.parse_args()
   if args.quiet:
@@ -165,12 +172,14 @@ def main():
   unmatched = queries.FillExpectationMapForCiBuilders(test_expectation_map,
                                                       ci_builders, args.suite,
                                                       args.project,
-                                                      args.num_samples)
+                                                      args.num_samples,
+                                                      args.large_query_mode)
   try_builders = builders.GetTryBuilders(ci_builders)
   unmatched.update(
       queries.FillExpectationMapForTryBuilders(test_expectation_map,
                                                try_builders, args.suite,
-                                               args.project, args.num_samples))
+                                               args.project, args.num_samples,
+                                               args.large_query_mode))
   unused_expectations = expectations.FilterOutUnusedExpectations(
       test_expectation_map)
   stale, semi_stale, active = expectations.SplitExpectationsByStaleness(