[ad-tagging] speculate DRYRUN for activation computation

This CL initializes main frame activation computating throttles with
a DRYRUN page activation, so they can speculatively access the ruleset
on start + redirects.

This should be the final CL to drive ActivationComputingDelay metrics
to 0.

Bug: 809504
Change-Id: If2b3e871cc97a00400e777081a8bace80f728e9f
Reviewed-on: https://chromium-review.googlesource.com/967663
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: Josh Karlin <jkarlin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545527}

chrome/browser/subresource_filter/subresource_filter_browsertest.cc

@@ -943,10 +943,14 @@ IN_PROC_BROWSER_TEST_F(SubresourceFilterBrowserTest,
 
 IN_PROC_BROWSER_TEST_F(SubresourceFilterBrowserTest,
                        ExpectHistogramsNotRecordedWhenFilteringNotActivated) {
-  ResetConfigurationToEnableOnPhishingSites(
-      true /* measure_performance */, false /* whitelist_site_on_reload */);
+  // This test only makes sense when AdTagging is disabled.
+  base::test::ScopedFeatureList scoped_tagging;
+  scoped_tagging.InitAndDisableFeature(kAdTagging);
   ASSERT_NO_FATAL_FAILURE(SetRulesetToDisallowURLsWithPathSuffix(
       "suffix-that-does-not-match-anything"));
+  ResetConfigurationToEnableOnPhishingSites(
+      true /* measure_performance */, false /* whitelist_site_on_reload */);
+
   const GURL url = GetTestUrl(kTestFrameSetPath);
   // Note: The |url| is not configured to be fishing.
 

components/subresource_filter/content/browser/content_subresource_filter_throttle_manager.cc

@@ -7,6 +7,7 @@
 #include <utility>
 
 #include "base/bind.h"
+#include "base/feature_list.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/stl_util.h"
@@ -20,6 +21,7 @@
 #include "components/subresource_filter/content/common/subresource_filter_messages.h"
 #include "components/subresource_filter/content/common/subresource_filter_utils.h"
 #include "components/subresource_filter/core/browser/subresource_filter_constants.h"
+#include "components/subresource_filter/core/browser/subresource_filter_features.h"
 #include "content/public/browser/navigation_handle.h"
 #include "content/public/browser/navigation_throttle.h"
 #include "content/public/browser/render_frame_host.h"
@@ -285,8 +287,14 @@ ContentSubresourceFilterThrottleManager::
         content::NavigationHandle* navigation_handle) {
   // Main frames: create unconditionally.
   if (navigation_handle->IsInMainFrame()) {
-    return ActivationStateComputingNavigationThrottle::CreateForMainFrame(
-        navigation_handle);
+    auto throttle =
+        ActivationStateComputingNavigationThrottle::CreateForMainFrame(
+            navigation_handle);
+    if (base::FeatureList::IsEnabled(kAdTagging)) {
+      throttle->NotifyPageActivationWithRuleset(
+          EnsureRulesetHandle(), ActivationState(ActivationLevel::DRYRUN));
+    }
+    return throttle;
   }
 
   // Subframes: create only for frames with activated parents.