Revert "Speculatively Revert "[url_pattern_index] Print matching rule for tracing""

This reverts commit a3bc216e.

Reason for revert: Reverting the CL did not fix the flaky test. See crbug.com/900606.

Original change's description:
> Speculatively Revert "[url_pattern_index] Print matching rule for tracing"
> 
> This reverts commit 1c7e7665.
> 
> Reason for revert:
> Fails test org.chromium.chrome.browser.SubresourceFilterTest#resourceFilteredClose
> See https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Android%20CFI/3471
> 
> Original change's description:
> > [url_pattern_index] Print matching rule for tracing
> > 
> > This is useful for debugging.
> > 
> > Bug: None
> > Change-Id: I8e6260f09b3c17f0a9952739387f70a431571011
> > Reviewed-on: https://chromium-review.googlesource.com/c/1308013
> > Commit-Queue: Charlie Harrison <csharrison@chromium.org>
> > Reviewed-by: Josh Karlin <jkarlin@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#603990}
> 
> TBR=jkarlin@chromium.org,csharrison@chromium.org
> 
> Change-Id: I44e487142ab5c3477ff77945a3f2854bb9762056
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: None
> Reviewed-on: https://chromium-review.googlesource.com/c/1308904
> Reviewed-by: Tarun Bansal <tbansal@chromium.org>
> Commit-Queue: Tarun Bansal <tbansal@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#604073}

TBR=jkarlin@chromium.org,tbansal@chromium.org,csharrison@chromium.org

Bug: 900606
Change-Id: Ibf69e14dfdc650776d542ce6334102b67317fa89
Reviewed-on: https://chromium-review.googlesource.com/c/1310115Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604295}

components/subresource_filter/tools/BUILD.gn

@@ -15,7 +15,7 @@ static_library("tools_lib") {
     "../core/browser",
     "../core/common",
     "//base",
-    "//components/url_pattern_index:util",
+    "//components/url_pattern_index",
     "//url",
   ]
 }

components/url_pattern_index/BUILD.gn

@@ -14,6 +14,8 @@ static_library("url_pattern_index") {
     "url_pattern.h",
     "url_pattern_index.cc",
     "url_pattern_index.h",
+    "url_rule_util.cc",
+    "url_rule_util.h",
   ]
 
   public_deps = [
@@ -44,17 +46,6 @@ static_library("test_support") {
   ]
 }
 
-static_library("util") {
-  sources = [
-    "url_rule_util.cc",
-    "url_rule_util.h",
-  ]
-  deps = [
-    ":url_pattern_index",
-    "//base",
-  ]
-}
-
 source_set("unit_tests") {
   testonly = true
   sources = [
@@ -69,7 +60,6 @@ source_set("unit_tests") {
   deps = [
     ":test_support",
     ":url_pattern_index",
-    ":util",
     "//base",
     "//testing/gtest",
     "//third_party/protobuf:protobuf_lite",

components/url_pattern_index/url_pattern_index.cc

@@ -17,8 +17,10 @@
 #include "base/optional.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
+#include "base/trace_event/trace_event.h"
 #include "components/url_pattern_index/ngram_extractor.h"
 #include "components/url_pattern_index/url_pattern.h"
+#include "components/url_pattern_index/url_rule_util.h"
 #include "url/gurl.h"
 #include "url/origin.h"
 #include "url/url_constants.h"
@@ -793,9 +795,15 @@ const flat::UrlRule* UrlPatternIndexMatcher::FindMatch(
     return nullptr;
   }
 
-  return FindMatchInFlatUrlPatternIndex(
+  auto* rule = FindMatchInFlatUrlPatternIndex(
       *flat_index_, UrlPattern::UrlInfo(url), first_party_origin, element_type,
       activation_type, is_third_party, disable_generic_rules, strategy);
+  if (rule) {
+    TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("loading"),
+                 "UrlPatternIndexMatcher::FindMatch", "pattern",
+                 FlatUrlRuleToFilterlistString(rule));
+  }
+  return rule;
 }
 
 }  // namespace url_pattern_index