Enable subresource redirect previews for CSS background images

This previews bit should be set only when SaveData is enabled and
irrespective of LazyLoad feature.

Bug: 1047330
Change-Id: I709b96b9518c449a7846634ff44c20b5bf96535d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2039895
Commit-Queue: rajendrant <rajendrant@chromium.org>
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Reviewed-by: Scott Little <sclittle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#743215}

third_party/blink/renderer/core/css/css_image_value.cc

@@ -20,6 +20,7 @@
 
 #include "third_party/blink/renderer/core/css/css_image_value.h"
 
+#include "third_party/blink/public/common/features.h"
 #include "third_party/blink/public/web/web_local_frame_client.h"
 #include "third_party/blink/renderer/core/css/css_markup.h"
 #include "third_party/blink/renderer/core/dom/document.h"
@@ -32,6 +33,7 @@
 #include "third_party/blink/renderer/platform/loader/fetch/fetch_parameters.h"
 #include "third_party/blink/renderer/platform/loader/fetch/resource_fetcher.h"
 #include "third_party/blink/renderer/platform/loader/fetch/resource_loader_options.h"
+#include "third_party/blink/renderer/platform/network/network_state_notifier.h"
 #include "third_party/blink/renderer/platform/weborigin/kurl.h"
 #include "third_party/blink/renderer/platform/weborigin/security_policy.h"
 
@@ -92,6 +94,14 @@ StyleImage* CSSImageValue::CacheImage(
       params.SetLazyImageDeferred();
     }
 
+    if (base::FeatureList::IsEnabled(blink::features::kSubresourceRedirect) &&
+        params.Url().ProtocolIsInHTTPFamily() &&
+        GetNetworkStateNotifier().SaveDataEnabled()) {
+      auto& resource_request = params.MutableResourceRequest();
+      resource_request.SetPreviewsState(resource_request.GetPreviewsState() |
+                                        WebURLRequest::kSubresourceRedirectOn);
+    }
+
     if (origin_clean_ != OriginClean::kTrue)
       params.SetFromOriginDirtyStyleSheet(true);
 

third_party/blink/renderer/core/html/BUILD.gn

@@ -693,6 +693,7 @@ blink_core_tests("unit_tests") {
     "parser/text_resource_decoder_test.cc",
     "portal/html_portal_element_test.cc",
     "shadow/progress_shadow_element_test.cc",
+    "subresource_redirect_test.cc",
     "time_ranges_test.cc",
     "track/text_track_list_test.cc",
     "track/vtt/buffered_line_reader_test.cc",

third_party/blink/renderer/core/html/subresource_redirect_test.cc

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <tuple>
+
+#include "base/test/scoped_feature_list.h"
+#include "third_party/blink/public/common/features.h"
+#include "third_party/blink/renderer/core/dom/document.h"
+#include "third_party/blink/renderer/core/frame/local_frame_view.h"
+#include "third_party/blink/renderer/core/frame/web_local_frame_impl.h"
+#include "third_party/blink/renderer/core/paint/paint_layer_scrollable_area.h"
+#include "third_party/blink/renderer/core/style/computed_style.h"
+#include "third_party/blink/renderer/core/style/style_image.h"
+#include "third_party/blink/renderer/core/testing/sim/sim_compositor.h"
+#include "third_party/blink/renderer/core/testing/sim/sim_request.h"
+#include "third_party/blink/renderer/core/testing/sim/sim_test.h"
+#include "third_party/blink/renderer/platform/loader/fetch/resource.h"
+#include "third_party/blink/renderer/platform/loader/fetch/resource_fetcher.h"
+#include "third_party/blink/renderer/platform/loader/fetch/resource_request.h"
+#include "third_party/blink/renderer/platform/network/network_state_notifier.h"
+#include "third_party/blink/renderer/platform/testing/unit_test_helpers.h"
+
+namespace blink {
+
+namespace {
+
+Vector<char> ReadTestImage() {
+  return test::ReadFromFile(test::CoreTestDataPath("notifications/500x500.png"))
+      ->CopyAs<Vector<char>>();
+}
+
+class SubresourceRedirectSimTest
+    : public ::testing::WithParamInterface<std::tuple<bool, bool, bool>>,
+      public SimTest {
+ protected:
+  SubresourceRedirectSimTest()
+      : scoped_lazy_image_loading_for_test_(is_lazyload_image_enabled()),
+        scoped_automatic_lazy_image_loading_for_test_(
+            is_lazyload_image_enabled()) {
+    if (is_subresource_redirect_enabled())
+      scoped_feature_list_.InitAndEnableFeature(features::kSubresourceRedirect);
+    GetNetworkStateNotifier().SetSaveDataEnabled(is_save_data_enabled());
+  }
+
+  bool is_subresource_redirect_enabled() { return std::get<0>(GetParam()); }
+
+  bool is_lazyload_image_enabled() { return std::get<1>(GetParam()); }
+
+  bool is_save_data_enabled() { return std::get<2>(GetParam()); }
+
+  void LoadMainResource(const String& html_body) {
+    SimRequest main_resource("https://example.com/", "text/html");
+    LoadURL("https://example.com/");
+
+    main_resource.Complete(html_body);
+    GetDocument().UpdateStyleAndLayoutTree();
+  }
+
+  ScopedLazyImageLoadingForTest scoped_lazy_image_loading_for_test_;
+  ScopedAutomaticLazyImageLoadingForTest
+      scoped_automatic_lazy_image_loading_for_test_;
+  base::test::ScopedFeatureList scoped_feature_list_;
+};
+
+// This test verifies subresource redirect previews state based on different
+// states of SaveData, LazyLoad, SubresourceRedirect features.
+TEST_P(SubresourceRedirectSimTest, CSSBackgroundImage) {
+  WebView().GetPage()->GetSettings().SetLazyLoadEnabled(
+      is_lazyload_image_enabled());
+
+  SimRequest image_resource("https://example.com/img.png", "image/png");
+  LoadMainResource(String::Format(R"HTML(
+        <style>
+        #deferred_image {
+          height:200px;
+          background-image: url('img.png');
+        }
+        </style>
+        <div style='height:10000px;'></div>
+        <div id="deferred_image"></div>
+      )HTML"));
+
+  if (!is_lazyload_image_enabled())
+    image_resource.Complete(ReadTestImage());
+
+  Compositor().BeginFrame();
+  test::RunPendingTasks();
+
+  if (is_lazyload_image_enabled()) {
+    // Scroll down until the background image is visible.
+    GetDocument().View()->LayoutViewport()->SetScrollOffset(
+        ScrollOffset(0, 10000), mojom::blink::ScrollType::kProgrammatic);
+    Compositor().BeginFrame();
+    test::RunPendingTasks();
+    image_resource.Complete(ReadTestImage());
+  }
+
+  WebURLRequest::PreviewsState previews_state =
+      GetDocument()
+          .Fetcher()
+          ->CachedResource(KURL("https://example.com/img.png"))
+          ->GetResourceRequest()
+          .GetPreviewsState();
+  // Subresource redirect previews bit should be set only if SaveData and
+  // SubresourceRedirect feature are enabled.
+  EXPECT_EQ(is_save_data_enabled() && is_subresource_redirect_enabled(),
+            (previews_state & WebURLRequest::kSubresourceRedirectOn) != 0);
+}
+
+INSTANTIATE_TEST_SUITE_P(
+    All,
+    SubresourceRedirectSimTest,
+    ::testing::Combine(::testing::Bool(), /* is_subresource_redirect_enabled */
+                       ::testing::Bool(), /* is_lazyload_image_enabled */
+                       ::testing::Bool()) /* is_save_data_enabled_*/);
+
+}  // namespace
+
+}  // namespace blink