Allow use of various field trial param functions in blink/renderer.

Change-Id: I0a9f90bcbb69cc6dd512ba6cb728ae285878e3b2
Reviewed-on: https://chromium-review.googlesource.com/1156336Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Fergal Daly <fergal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579371}

third_party/blink/renderer/DEPS

@@ -12,6 +12,7 @@ include_rules = [
     "+base/memory/ptr_util.h",
     "+base/memory/weak_ptr.h",
     "+base/metrics/histogram_macros.h",
+    "+base/metrics/field_trial_params.h",
     "+base/numerics/checked_math.h",
     "+base/numerics/safe_conversions.h",
     "+base/optional.h",

third_party/blink/tools/audit_non_blink_usage.py

@@ -77,6 +77,12 @@ _CONFIG = [
             # //base/memory/ptr_util.h.
             'base::WrapUnique',
 
+            # //base/metrics/field_trial_params.h.
+            'base::GetFieldTrialParamValueByFeature',
+            'base::GetFieldTrialParamByFeatureAsBool',
+            'base::GetFieldTrialParamByFeatureAsDouble',
+            'base::GetFieldTrialParamByFeatureAsInt',
+
             # //base/numerics/safe_conversions.h.
             'base::as_signed',
             'base::as_unsigned',