Add instrumentation hooks to mesaure which subresource filter rules are used.

components/subresource_filter/content/renderer/subresource_filter_agent.cc

Index: components/subresource_filter/content/renderer/subresource_filter_agent.cc
diff --git a/components/subresource_filter/content/renderer/subresource_filter_agent.cc b/components/subresource_filter/content/renderer/subresource_filter_agent.cc
index c9b47d511775592418c01a6abfaaae09d69e9a07..b1abe7f9b50332551789cdc76eb2c34ed10c2156 100644
--- a/components/subresource_filter/content/renderer/subresource_filter_agent.cc
+++ b/components/subresource_filter/content/renderer/subresource_filter_agent.cc
@@ -61,6 +61,7 @@ void SubresourceFilterAgent::SendDocumentLoadStatistics(
 
 void SubresourceFilterAgent::OnActivateForNextCommittedLoad(
     ActivationState activation_state) {
+  LOG(ERROR) << "OnActivateForNextCommittedLoad";
   activation_state_for_next_commit_ = activation_state;
 }
 
@@ -142,8 +143,13 @@ void SubresourceFilterAgent::DidCommitProvisionalLoad(
   // TODO(csharrison): Use WebURL and WebSecurityOrigin for efficiency here,
   // which require changes to the unit tests.
   const GURL& url = GetDocumentURL();
+
   if (url.SchemeIsHTTPOrHTTPS() || url.SchemeIsFile()) {
     RecordHistogramsOnLoadCommitted();
+    LOG(ERROR) << "Commiting "
+               << activation_state_for_next_commit_.activation_level << " "
+               << url;
+
     if (activation_state_for_next_commit_.activation_level !=
             ActivationLevel::DISABLED &&
         ruleset_dealer_->IsRulesetFileAvailable()) {