Enables ResourceLoading preview by default on Android

Bug: 929501
Change-Id: Iedb98ca6909f8832caf5b387eca7a9e503ed006c
Reviewed-on: https://chromium-review.googlesource.com/c/1457717Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Doug Arnett <dougarnett@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630338}

components/previews/content/previews_content_util_unittest.cc

@@ -432,8 +432,7 @@ TEST_F(PreviewsContentUtilTest,
   EXPECT_EQ(content::CLIENT_LOFI_ON,
             previews::DetermineCommittedClientPreviewsState(
                 &user_data, GURL("https://www.google.com"),
-                content::CLIENT_LOFI_ON | content::NOSCRIPT_ON |
-                    content::RESOURCE_LOADING_HINTS_ON,
+                content::CLIENT_LOFI_ON | content::NOSCRIPT_ON,
                 enabled_previews_decider()));
 }
 

components/previews/content/previews_decider_impl_unittest.cc

@@ -1125,7 +1125,7 @@ TEST_F(PreviewsDeciderImplTest, LitePageRedirectDisallowedByServerBlacklist) {
       1);
 }
 
-TEST_F(PreviewsDeciderImplTest, ResourceLoadingHintsDisallowedByDefault) {
+TEST_F(PreviewsDeciderImplTest, ResourceLoadingHintsAllowedByDefault) {
   base::test::ScopedFeatureList scoped_feature_list;
   scoped_feature_list.InitWithFeatures(
       {features::kPreviews, features::kOptimizationHints}, {});
@@ -1133,7 +1133,14 @@ TEST_F(PreviewsDeciderImplTest, ResourceLoadingHintsDisallowedByDefault) {
 
   base::HistogramTester histogram_tester;
   PreviewsUserData user_data(kDefaultPageId);
-  EXPECT_FALSE(previews_decider_impl()->ShouldAllowPreviewAtNavigationStart(
+
+#if defined(OS_ANDROID)
+  bool expected = true;
+#else   // !defined(OS_ANDROID)
+  bool expected = false;
+#endif  // defined(OS_ANDROID)
+  EXPECT_EQ(expected,
+            previews_decider_impl()->ShouldAllowPreviewAtNavigationStart(
                 &user_data, GURL("https://www.google.com"), false,
                 PreviewsType::RESOURCE_LOADING_HINTS));
 }

components/previews/core/previews_features.cc

@@ -74,8 +74,14 @@ const base::Feature kOptimizationHintsExperiments{
     "OptimizationHintsExperiments", base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enables the application of the resource loading hints when loading resources.
-const base::Feature kResourceLoadingHints{"ResourceLoadingHints",
-                                          base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kResourceLoadingHints {
+  "ResourceLoadingHints",
+#if defined(OS_ANDROID)
+      base::FEATURE_ENABLED_BY_DEFAULT
+#else   // !defined(OS_ANDROID)
+      base::FEATURE_DISABLED_BY_DEFAULT
+#endif  // defined(OS_ANDROID)
+};
 
 // Enables client redirects to a server-rendered lite page preview.
 const base::Feature kLitePageServerPreviews{"LitePageServerPreviews",