Add custom swarming timeouts for chromium.perf.* tests.

tools/perf/generate_perf_json.py

Index: tools/perf/generate_perf_json.py
diff --git a/tools/perf/generate_perf_json.py b/tools/perf/generate_perf_json.py
index 78194218ccd834a13c8d80dd02a760f09a3f9406..db537a10cc896378680e26957d7ebf74f5ff72ba 100755
--- a/tools/perf/generate_perf_json.py
+++ b/tools/perf/generate_perf_json.py
@@ -438,7 +438,8 @@ def get_waterfall_config():
 
 
 def generate_isolate_script_entry(swarming_dimensions, test_args,
-  isolate_name, step_name, override_compile_targets=None):
+    isolate_name, step_name, override_compile_targets=None,
+    swarming_timeout=None):
   result = {
     'args': test_args,
     'isolate_name': isolate_name,
@@ -452,7 +453,7 @@ def generate_isolate_script_entry(swarming_dimensions, test_args,
       # supports swarming. It doesn't hurt.
       'can_use_on_swarming_builders': True,
       'expiration': 21600,
-      'hard_timeout': 7200,
+      'hard_timeout': swarming_timeout if swarming_timeout else 7200,
       'io_timeout': 3600,
       'dimension_sets': swarming_dimensions,
     }
@@ -482,7 +483,8 @@ def generate_telemetry_test(swarming_dimensions, benchmark_name, browser):
 
   return generate_isolate_script_entry(
     swarming_dimensions, test_args, 'telemetry_perf_tests',
-    step_name, ['telemetry_perf_tests'])
+    step_name, ['telemetry_perf_tests'],
+    swarming_timeout=BENCHMARK_SWARMING_TIMEOUTS.get(benchmark_name))
 
 
 def script_test_enabled_on_tester(master, test, tester_name, shard):
@@ -602,6 +604,11 @@ BENCHMARK_NAME_BLACKLIST = [
     'skpicture_printer_ct',
 ]
 
+# Overrides the default 2 hour timeout for swarming tasks.
+BENCHMARK_SWARMING_TIMEOUTS = {
+    'loading.mobile': 14400,
+}
+
 # Certain swarming bots are not sharding correctly with the new device affinity
 # algorithm.  Reverting to legacy algorithm to try and get them to complete.
 # See crbug.com/670284