Adds experiment_name support to PageHint based previews.

Checks experiment_name field on Optimization defined at PageHint
level and only whitelists if that experiment name is enabled for
the client.

Bug: 888666
Change-Id: I42425aaf9403a023d684c94ce94860cba27513f2
Reviewed-on: https://chromium-review.googlesource.com/1241214Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Doug Arnett <dougarnett@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594384}

components/previews/content/previews_hints.cc

@@ -250,6 +250,11 @@ std::unique_ptr<PreviewsHints> PreviewsHints::CreateFromConfig(
 
       for (const auto& page_hint : hint.page_hints()) {
         for (const auto& optimization : page_hint.whitelisted_optimizations()) {
+          if (IsDisabledExperimentalOptimization(optimization)) {
+            // This is an experimental optimization that is not enabled so
+            // continue in case there is a non-experimental one.
+            continue;
+          }
           base::Optional<PreviewsType> previews_type =
               ConvertProtoOptimizationTypeToPreviewsOptimizationType(
                   optimization.optimization_type());
@@ -442,6 +447,11 @@ bool PreviewsHints::IsWhitelisted(const GURL& url,
        matched_page_hint->whitelisted_optimizations()) {
     if (ConvertProtoOptimizationTypeToPreviewsOptimizationType(
             optimization.optimization_type()) == type) {
+      if (IsDisabledExperimentalOptimization(optimization)) {
+        // This is an experimental optimization that is not enabled so continue
+        // in case there is a non-experimental one.
+        continue;
+      }
       *out_inflation_percent = optimization.inflation_percent();
       return true;
     }

components/previews/content/previews_hints_unittest.cc

@@ -41,6 +41,7 @@ class PreviewsHintsTest : public testing::Test {
         base::Version("1.0"),
         temp_dir_.GetPath().Append(FILE_PATH_LITERAL("somefile.pb")));
     previews_hints_ = PreviewsHints::CreateFromConfig(config, info);
+    previews_hints_->Initialize();
   }
 
   PreviewsHints* previews_hints() { return previews_hints_.get(); }
@@ -217,4 +218,64 @@ TEST_F(PreviewsHintsTest, ParseConfigWithTooLargeBlacklist) {
       GURL("https://black.com/path"), PreviewsType::LITE_PAGE_REDIRECT));
 }
 
+TEST_F(PreviewsHintsTest, IsWhitelistedForExperimentalPreview) {
+  base::test::ScopedFeatureList scoped_list;
+  scoped_list.InitAndEnableFeature(features::kResourceLoadingHints);
+  optimization_guide::proto::Configuration config;
+
+  optimization_guide::proto::Hint* hint1 = config.add_hints();
+  hint1->set_key("somedomain.org");
+  hint1->set_key_representation(optimization_guide::proto::HOST_SUFFIX);
+
+  // Page hint for "/experimental_preview/"
+  optimization_guide::proto::PageHint* page_hint1 = hint1->add_page_hints();
+  page_hint1->set_page_pattern("/experimental_preview/");
+  // First add experimental PageHint optimization.
+  optimization_guide::proto::Optimization* experimental_optimization =
+      page_hint1->add_whitelisted_optimizations();
+  experimental_optimization->set_experiment_name("foo_experiment");
+  experimental_optimization->set_inflation_percent(99);
+  experimental_optimization->set_optimization_type(
+      optimization_guide::proto::RESOURCE_LOADING);
+  optimization_guide::proto::ResourceLoadingHint* experimental_resourcehint =
+      experimental_optimization->add_resource_loading_hints();
+  experimental_resourcehint->set_loading_optimization_type(
+      optimization_guide::proto::LOADING_BLOCK_RESOURCE);
+  experimental_resourcehint->set_resource_pattern("experimental_resource.js");
+  // Add a non-experimental PageHint optimization with same resource pattern.
+  optimization_guide::proto::Optimization* default_pagehint_optimization =
+      page_hint1->add_whitelisted_optimizations();
+  default_pagehint_optimization->set_inflation_percent(33);
+  default_pagehint_optimization->set_optimization_type(
+      optimization_guide::proto::RESOURCE_LOADING);
+  optimization_guide::proto::ResourceLoadingHint* default_resourcehint =
+      default_pagehint_optimization->add_resource_loading_hints();
+  default_resourcehint->set_loading_optimization_type(
+      optimization_guide::proto::LOADING_BLOCK_RESOURCE);
+  default_resourcehint->set_resource_pattern("experimental_resource.js");
+  ParseConfig(config);
+
+  // Verify default resource hint whitelisted (via inflation_percent).
+  int inflation_percent;
+  EXPECT_TRUE(previews_hints()->IsWhitelisted(
+      GURL("https://www.somedomain.org/experimental_preview/"
+           "experimental_resource.js"),
+      PreviewsType::RESOURCE_LOADING_HINTS, &inflation_percent));
+  EXPECT_EQ(33, inflation_percent);
+
+  // Now enable the experiment and verify experimental resource hint chosen.
+  {
+    base::test::ScopedFeatureList scoped_list2;
+    scoped_list2.InitAndEnableFeatureWithParameters(
+        features::kOptimizationHintsExperiments,
+        {{"experiment_name", "foo_experiment"}});
+    int inflation_percent;
+    EXPECT_TRUE(previews_hints()->IsWhitelisted(
+        GURL("https://www.somedomain.org/experimental_preview/"
+             "experimental_resource.js"),
+        PreviewsType::RESOURCE_LOADING_HINTS, &inflation_percent));
+    EXPECT_EQ(99, inflation_percent);
+  }
+}
+
 }  // namespace previews