Enabled NoScript Preview feature by default on Android

This is in conjunction with launching NoScript Preview
to Stable channel via Finch.

Bug: 876778
Change-Id: Ibc5f559b4c4b36555fc04966c8c44a4cccdb381d
Reviewed-on: https://chromium-review.googlesource.com/1185369
Commit-Queue: Doug Arnett <dougarnett@chromium.org>
Reviewed-by: Ryan Sturm <ryansturm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585490}

chrome/browser/previews/previews_service_unittest.cc

@@ -16,6 +16,7 @@
 #include "base/single_thread_task_runner.h"
 #include "base/test/scoped_feature_list.h"
 #include "base/time/default_clock.h"
+#include "build/build_config.h"
 #include "components/blacklist/opt_out_blacklist/opt_out_blacklist_data.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_features.h"
 #include "components/previews/content/previews_decider_impl.h"
@@ -187,8 +188,12 @@ TEST_F(PreviewsServiceTest, TestLitePageProxyDecidesTransform) {
 }
 
 TEST_F(PreviewsServiceTest, TestNoScriptPreviewsEnabledByFeature) {
+#if !defined(OS_ANDROID)
+  // For non-android, default is disabled.
   EXPECT_FALSE(previews_decider_impl()->IsPreviewEnabled(
       previews::PreviewsType::NOSCRIPT));
+#endif  // defined(OS_ANDROID)
+
   base::test::ScopedFeatureList scoped_feature_list;
   scoped_feature_list.InitAndEnableFeature(
       previews::features::kNoScriptPreviews);

components/previews/content/previews_content_util_unittest.cc

@@ -223,7 +223,8 @@ TEST_F(PreviewsContentUtilTest, DetermineCommittedClientPreviewsState) {
 TEST_F(PreviewsContentUtilTest,
        DetermineCommittedClientPreviewsStateNoScriptCheckIfStillAllowed) {
   base::test::ScopedFeatureList scoped_feature_list;
-  scoped_feature_list.InitFromCommandLine("Previews,ClientLoFi", std::string());
+  scoped_feature_list.InitFromCommandLine("Previews,ClientLoFi",
+                                          "NoScriptPreviews");
   // NoScript not allowed at commit time so Client LoFi chosen:
   EXPECT_EQ(content::PREVIEWS_OFF,
             previews::DetermineCommittedClientPreviewsState(

components/previews/content/previews_decider_impl_unittest.cc

@@ -27,6 +27,7 @@
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/default_clock.h"
 #include "base/time/time.h"
+#include "build/build_config.h"
 #include "components/blacklist/opt_out_blacklist/opt_out_blacklist_data.h"
 #include "components/blacklist/opt_out_blacklist/opt_out_blacklist_delegate.h"
 #include "components/blacklist/opt_out_blacklist/opt_out_blacklist_item.h"
@@ -836,7 +837,7 @@ TEST_F(PreviewsDeciderImplTest, ClientLoFiObeysHostBlackListFromServer) {
   }
 }
 
-TEST_F(PreviewsDeciderImplTest, NoScriptDisallowedByDefault) {
+TEST_F(PreviewsDeciderImplTest, NoScriptFeatureDefaultBehavior) {
   base::test::ScopedFeatureList scoped_feature_list;
   scoped_feature_list.InitAndEnableFeature(features::kPreviews);
   InitializeUIService();
@@ -850,13 +851,25 @@ TEST_F(PreviewsDeciderImplTest, NoScriptDisallowedByDefault) {
       previews::params::GetECTThresholdForPreview(
           previews::PreviewsType::NOSCRIPT),
       std::vector<std::string>(), false));
+#if defined(OS_ANDROID)
+  // Enabled by default on Android but no server whitelist.
+  histogram_tester.ExpectTotalCount("Previews.EligibilityReason.NoScript", 1);
+  histogram_tester.ExpectUniqueSample(
+      "Previews.EligibilityReason.NoScript",
+      static_cast<int>(
+          PreviewsEligibilityReason::HOST_NOT_WHITELISTED_BY_SERVER),
+      1);
+#else   // !defined(OS_ANDROID)
+  // Disabled by default on non-Android.
   histogram_tester.ExpectTotalCount("Previews.EligibilityReason.NoScript", 0);
+#endif  // defined(OS_ANDROID)
 }
 
 TEST_F(PreviewsDeciderImplTest, NoScriptAllowedByFeature) {
   base::test::ScopedFeatureList scoped_feature_list;
   scoped_feature_list.InitWithFeatures(
-      {features::kPreviews, features::kNoScriptPreviews}, {});
+      {features::kPreviews, features::kNoScriptPreviews},
+      {features::kOptimizationHints});
   InitializeUIService();
 
   const struct {
@@ -999,7 +1012,8 @@ TEST_F(PreviewsDeciderImplTest,
        ResourceLoadingHintsDisallowedWithoutOptimizationHints) {
   base::test::ScopedFeatureList scoped_feature_list;
   scoped_feature_list.InitWithFeatures(
-      {features::kPreviews, features::kResourceLoadingHints}, {});
+      {features::kPreviews, features::kResourceLoadingHints},
+      {features::kOptimizationHints});
   InitializeUIService();
 
   network_quality_estimator()->set_effective_connection_type(
@@ -1314,7 +1328,8 @@ TEST_F(PreviewsDeciderImplTest, LogDecisionMadeBlacklistStatusesDefault) {
 TEST_F(PreviewsDeciderImplTest, IsURLAllowedForPreviewBlacklistStatuses) {
   base::test::ScopedFeatureList scoped_feature_list;
   scoped_feature_list.InitWithFeatures(
-      {features::kPreviews, features::kNoScriptPreviews}, {});
+      {features::kPreviews, features::kNoScriptPreviews},
+      {features::kOptimizationHints});
   InitializeUIService();
   auto expected_type = PreviewsType::NOSCRIPT;
 

components/previews/core/previews_features.cc

@@ -37,8 +37,14 @@ const base::Feature kClientLoFi {
 };
 
 // Enables the NoScript previews for Android.
-const base::Feature kNoScriptPreviews{"NoScriptPreviews",
-                                      base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kNoScriptPreviews {
+  "NoScriptPreviews",
+#if defined(OS_ANDROID)
+      base::FEATURE_ENABLED_BY_DEFAULT
+#else   // !defined(OS_ANDROID)
+      base::FEATURE_DISABLED_BY_DEFAULT
+#endif  // defined(OS_ANDROID)
+};
 
 // Enables the Stale Previews timestamp on Previews infobars.
 const base::Feature kStalePreviewsTimestamp{"StalePreviewsTimestamp",
@@ -46,8 +52,14 @@ const base::Feature kStalePreviewsTimestamp{"StalePreviewsTimestamp",
 
 // Enables the syncing of the Optimization Hints component, which provides
 // hints for what Previews can be applied on a page load.
-const base::Feature kOptimizationHints{"OptimizationHints",
-                                       base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kOptimizationHints {
+  "OptimizationHints",
+#if defined(OS_ANDROID)
+      base::FEATURE_ENABLED_BY_DEFAULT
+#else   // !defined(OS_ANDROID)
+      base::FEATURE_DISABLED_BY_DEFAULT
+#endif  // defined(OS_ANDROID)
+};
 
 // Enables Optimization Hints that are marked as experimental. Optimizations are
 // marked experimental by setting an experiment name in the "experiment_name"