Remove FeaturePolicyForPermissions

The flag has been removed from RuntimeEnabledFeatures, so this change
eliminates a warning message on startup.

Change-Id: I8f6f8027f7f0446a5cf3c03f0740cd90277a7ecf
Reviewed-on: https://chromium-review.googlesource.com/1173255Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Ian Clelland <iclelland@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582897}

content/child/runtime_features.cc

@@ -411,10 +411,6 @@ void SetRuntimeFeaturesDefaultsAndUpdateFromArgs(
   WebRuntimeFeatures::EnableScheduledScriptStreaming(
       base::FeatureList::IsEnabled(features::kScheduledScriptStreaming));
 
-  WebRuntimeFeatures::EnableFeatureFromString(
-      "FeaturePolicyForPermissions",
-      base::FeatureList::IsEnabled(features::kUseFeaturePolicyForPermissions));
-
   if (base::FeatureList::IsEnabled(features::kLazyFrameLoading))
     WebRuntimeFeatures::EnableLazyFrameLoading(true);
   if (base::FeatureList::IsEnabled(features::kLazyFrameVisibleLoadTimeMetrics))