Add high-precision timing histograms.

components/subresource_filter/content/renderer/document_subresource_filter.cc

Index: components/subresource_filter/content/renderer/document_subresource_filter.cc
diff --git a/components/subresource_filter/content/renderer/document_subresource_filter.cc b/components/subresource_filter/content/renderer/document_subresource_filter.cc
index 8888befb49ba342179c3f37c9d36f25173cef645..fc8a51ea71ec90297e0e7aa25a147b83cbee69a6 100644
--- a/components/subresource_filter/content/renderer/document_subresource_filter.cc
+++ b/components/subresource_filter/content/renderer/document_subresource_filter.cc
@@ -12,6 +12,7 @@
 #include "base/trace_event/trace_event.h"
 #include "components/subresource_filter/core/common/first_party_origin.h"
 #include "components/subresource_filter/core/common/memory_mapped_ruleset.h"
+#include "components/subresource_filter/core/common/scoped_uma_histogram_timers.h"
 #include "third_party/WebKit/public/platform/WebURL.h"
 
 namespace subresource_filter {
@@ -87,6 +88,11 @@ DocumentSubresourceFilter::DocumentSubresourceFilter(
                                    ? std::string()
                                    : ancestor_document_urls[0].spec());
 
+  SCOPED_UMA_HISTOGRAM_MICRO_TIMER(
+      "SubresourceFilter.DocumentLoad.Activation.WallDuration");
+  SCOPED_UMA_HISTOGRAM_MICRO_THREAD_TIMER(
+      "SubresourceFilter.DocumentLoad.Activation.CPUDuration");
+
   DCHECK_NE(activation_state_, ActivationState::DISABLED);
   DCHECK(ruleset);
 
@@ -124,6 +130,11 @@ bool DocumentSubresourceFilter::allowLoad(
   TRACE_EVENT1("loader", "DocumentSubresourceFilter::allowLoad", "url",
                resourceUrl.string().utf8());
 
+  SCOPED_UMA_HISTOGRAM_MICRO_TIMER(
+      "SubresourceFilter.SubresourceLoad.Evaluation.WallDuration");
+  SCOPED_UMA_HISTOGRAM_MICRO_THREAD_TIMER(
+      "SubresourceFilter.SubresourceLoad.Evaluation.CPUDuration");
+
   ++num_loads_total_;
 
   if (filtering_disabled_for_document_)