Add a module for tracking categories that metrics depend on.

tools/perf/benchmarks/loading.py

Index: tools/perf/benchmarks/loading.py
diff --git a/tools/perf/benchmarks/loading.py b/tools/perf/benchmarks/loading.py
index 167f4eb65f74209f9d0f23cc50eb1df13fa71e09..2b4d14e0df890ac983cad2f6c39455c3a9e52b74 100644
--- a/tools/perf/benchmarks/loading.py
+++ b/tools/perf/benchmarks/loading.py
@@ -6,7 +6,7 @@ from core import perf_benchmark
 import page_sets
 
 import ct_benchmarks_util
-from benchmarks import page_cycler_v2
+from benchmarks import metric_dependencies
 from telemetry import benchmark
 from telemetry.page import cache_temperature
 from telemetry.page import traffic_setting
@@ -21,7 +21,8 @@ class LoadingMobile(perf_benchmark.PerfBenchmark):
 
   def CreateTimelineBasedMeasurementOptions(self):
     tbm_options = timeline_based_measurement.Options()
-    page_cycler_v2.AugmentOptionsForLoadingMetrics(tbm_options)
+    tbm_options.SetTimelineBasedMetrics(['loadingMetric'])
+    metric_dependencies.AugmentOptionsForMetrics(tbm_options, ['loadingMetric'])
     return tbm_options
 
   @classmethod
@@ -59,7 +60,8 @@ class LoadingClusterTelemetry(perf_benchmark.PerfBenchmark):
 
   def CreateTimelineBasedMeasurementOptions(self):
     tbm_options = timeline_based_measurement.Options()
-    page_cycler_v2.AugmentOptionsForLoadingMetrics(tbm_options)
+    tbm_options.SetTimelineBasedMetrics(['loadingMetric'])
+    metric_dependencies.AugmentOptionsForMetrics(tbm_options, ['loadingMetric'])
     return tbm_options
 
   @classmethod