Add a feature for Simplified URL Display experiments

Simplified URL Display experiments have five populations:
1. Default group
2. Control group
3. Delayed Warnings only
4. Experiment group 1
5. Experiment group 2

Default and Control groups don't set any of the bits in the
UrlDisplayExperiment proto, so it's impossible to distinguish them in
the analysis stage.

To address this issue, this CL adds SimplifiedUrlDisplay feature. This
feature doesn't turn on any features itself. Instead, it will be enabled
by a server side config for all display experiments except for the
default group. This way, the new bit in the URLDisplayExperiment proto
will allow us to differentiate between the default group and control
group.

Bug: 1132457
Change-Id: Ie45545248b9ad1a15c774158a30e5162a6911a63
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2432054
Commit-Queue: Mustafa Emre Acer <meacer@chromium.org>
Reviewed-by: Daniel Rubery <drubery@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812457}

chrome/browser/safe_browsing/chrome_password_protection_service.cc

@@ -359,6 +359,8 @@ bool ChromePasswordProtectionService::ShouldShowPasswordReusePageInfoBubble(
 safe_browsing::LoginReputationClientRequest::UrlDisplayExperiment
 ChromePasswordProtectionService::GetUrlDisplayExperiment() const {
   safe_browsing::LoginReputationClientRequest::UrlDisplayExperiment experiment;
+  experiment.set_simplified_url_display_enabled(
+      base::FeatureList::IsEnabled(safe_browsing::kSimplifiedUrlDisplay));
   // Delayed warnings parameters:
   experiment.set_delayed_warnings_enabled(
       base::FeatureList::IsEnabled(safe_browsing::kDelayedWarnings));

components/safe_browsing/core/features.cc

@@ -47,6 +47,9 @@ const base::FeatureParam<bool> kDelayedWarningsEnableMouseClicks{
     &kDelayedWarnings, "mouse",
     /*default_value=*/false};
 
+const base::Feature kSimplifiedUrlDisplay{"SimplifiedUrlDisplay",
+                                          base::FEATURE_DISABLED_BY_DEFAULT};
+
 const base::Feature kDownloadRequestWithToken{
     "SafeBrowsingDownloadRequestWithToken", base::FEATURE_ENABLED_BY_DEFAULT};
 

components/safe_browsing/core/features.h

@@ -136,6 +136,12 @@ extern const base::Feature kDelayedWarnings;
 // warnings feature is enabled.
 extern const base::FeatureParam<bool> kDelayedWarningsEnableMouseClicks;
 
+// Status of the SimplifiedUrlDisplay experiments. This does not control the
+// individual experiments, those are controlled by their own feature flags.
+// The feature is only set by Finch so that we can differentiate between
+// default and control groups of the experiment.
+extern const base::Feature kSimplifiedUrlDisplay;
+
 base::ListValue GetFeatureStatusList();
 
 // Returns whether or not to stop filling in the SyncAccountType and

components/safe_browsing/core/proto/csd.proto

@@ -366,6 +366,8 @@ message LoginReputationClientRequest {
     optional bool hide_on_interaction = 4;
     // True if OmniboxUIExperimentElideToRegistrableDomain is enabled.
     optional bool elide_to_registrable_domain = 5;
+    // True if this is the control group. This sent by the finch config.
+    optional bool simplified_url_display_enabled = 6;
   };
   optional UrlDisplayExperiment url_display_experiment = 14;
 }