[editing] Move caret when navigating to a fragment with caret browsing

When navigating to #foo, the element with id="foo" is scrolled into view
and is focused if focusable. This patch makes it receive the caret too,
in case caret browsing is enabled.

Bug: 1011934

TEST=editing/caret/caret-browsing-fragment-anchor.html

Change-Id: I044e6b48545426afdb0c5ee766d4ee3a218aa95b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2463308
Commit-Queue: Oriol Brufau <obrufau@igalia.com>
Reviewed-by: danakj <danakj@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843064}

content/web_test/renderer/test_runner.cc

@@ -279,6 +279,7 @@ class TestRunnerBindings : public gin::Wrappable<TestRunnerBindings> {
                                v8::Local<v8::Function> callback);
   void SetBluetoothManualChooser(bool enable);
   void SetCanOpenWindows();
+  void SetCaretBrowsingEnabled();
   void SetColorProfile(const std::string& name,
                        v8::Local<v8::Function> callback);
   void SetCustomPolicyDelegate(gin::Arguments* args);
@@ -669,6 +670,8 @@ gin::ObjectTemplateBuilder TestRunnerBindings::GetObjectTemplateBuilder(
                  &TestRunnerBindings::SetBluetoothManualChooser)
       .SetMethod("setCallCloseOnWebViews", &TestRunnerBindings::NotImplemented)
       .SetMethod("setCanOpenWindows", &TestRunnerBindings::SetCanOpenWindows)
+      .SetMethod("setCaretBrowsingEnabled",
+                 &TestRunnerBindings::SetCaretBrowsingEnabled)
       .SetMethod("setColorProfile", &TestRunnerBindings::SetColorProfile)
       .SetMethod("setCustomPolicyDelegate",
                  &TestRunnerBindings::SetCustomPolicyDelegate)
@@ -1470,6 +1473,13 @@ void TestRunnerBindings::SetCanOpenWindows() {
   runner_->SetCanOpenWindows();
 }
 
+void TestRunnerBindings::SetCaretBrowsingEnabled() {
+  if (invalid_)
+    return;
+  blink::WebView* web_view = GetWebFrame()->View();
+  web_view->GetSettings()->SetCaretBrowsingEnabled(true);
+}
+
 void TestRunnerBindings::SetImagesAllowed(bool allowed) {
   if (invalid_)
     return;
@@ -2301,6 +2311,7 @@ void TestRunner::ResetWebView(WebViewTestProxy* web_view_test_proxy) {
 
   web_view->SetTabKeyCyclesThroughElements(true);
   web_view->GetSettings()->SetHighlightAds(false);
+  web_view->GetSettings()->SetCaretBrowsingEnabled(false);
   web_view->DisableAutoResizeForTesting(gfx::Size());
   web_view->SetScreenOrientationOverrideForTesting(
       fake_screen_orientation_impl_.CurrentOrientationType());

third_party/blink/renderer/core/page/scrolling/element_fragment_anchor.cc

@@ -11,6 +11,7 @@
 #include "third_party/blink/renderer/core/dom/element.h"
 #include "third_party/blink/renderer/core/dom/events/event.h"
 #include "third_party/blink/renderer/core/dom/node.h"
+#include "third_party/blink/renderer/core/editing/frame_selection.h"
 #include "third_party/blink/renderer/core/execution_context/execution_context.h"
 #include "third_party/blink/renderer/core/frame/local_frame.h"
 #include "third_party/blink/renderer/core/svg/svg_svg_element.h"
@@ -174,11 +175,27 @@ void ElementFragmentAnchor::ApplyFocusIfNeeded() {
   if (!anchor_node_)
     return;
 
+  frame_->GetDocument()->UpdateStyleAndLayoutTree();
+
+  // If caret browsing is enabled, move the caret to the beginning of the
+  // fragment, or to the first non-inert position after it.
+  if (frame_->IsCaretBrowsingEnabled()) {
+    const Position& pos = Position::FirstPositionInOrBeforeNode(*anchor_node_);
+    if (pos.IsConnected()) {
+      frame_->Selection().SetSelection(
+          SelectionInDOMTree::Builder().Collapse(pos).Build(),
+          SetSelectionOptions::Builder()
+              .SetShouldCloseTyping(true)
+              .SetShouldClearTypingStyle(true)
+              .SetDoNotSetFocus(true)
+              .Build());
+    }
+  }
+
   // If the anchor accepts keyboard focus and fragment scrolling is allowed,
   // move focus there to aid users relying on keyboard navigation.
   // If anchorNode is not focusable or fragment scrolling is not allowed,
   // clear focus, which matches the behavior of other browsers.
-  frame_->GetDocument()->UpdateStyleAndLayoutTree();
   auto* element = DynamicTo<Element>(anchor_node_.Get());
   if (element && element->IsFocusable()) {
     element->focus();

third_party/blink/web_tests/editing/caret/caret-browsing-fragment-anchor.html

+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>Caret browsing with fragment anchor navigation</title>
+<link rel="author" title="Oriol Brufau" href="mailto:obrufau@igalia.com">
+<meta name="assert" content="
+  This test checks that, when caret browsing is enabled, navigating to a fragment moves
+  the caret to the beginning of the fragment. Or, if the fragment is inert, to the next
+  non-inert position (which may be out of view, since it's the fragment what's scrolled
+  into view, not the caret).
+" />
+<style>
+.separator {
+  margin: 50vh 0;
+}
+</style>
+<div class="separator">Content 1</div>
+<div class="test" id="normal">Normal</div>
+<div class="separator">Content 2</div>
+<div class="test" id="focusable" tabindex="-1" data-focusable>Focusable</div>
+<div class="separator">Content 3</div>
+<div class="test" id="inert" inert data-caret-target="after-inert">Inert</div>
+<div class="separator" id="after-inert">Content 4</div>
+<div inert>
+  <div class="separator">Content 5</div>
+  <div class="test" id="inside-inert" data-caret-target="after-inside-inert">Inside inert</div>
+  <div class="separator">Content 6</div>
+</div>
+<div class="separator" id="after-inside-inert">Content 7</div>
+<div id="log"></div>
+<script src="../../resources/testharness.js"></script>
+<script src="../../resources/testharnessreport.js"></script>
+<script>
+function setHash(hash) {
+  return new Promise((resolve) => {
+    addEventListener("hashchange", resolve, {once: true});
+    location.hash = "#" + hash;
+  });
+}
+if (window.testRunner) {
+  testRunner.setCaretBrowsingEnabled();
+}
+const selection = getSelection();
+const scroller = document.scrollingElement;
+for (let target of document.querySelectorAll(".test")) {
+  promise_test(async (t) => {
+    await setHash(target.id);
+
+    // Check scroll offset
+    const actualScrollOffset = scroller.scrollTop;
+    target.scrollIntoView();
+    const expectedScrollOffset = scroller.scrollTop;
+    assert_equals(actualScrollOffset, expectedScrollOffset, "Scrolled into view");
+
+    // Check focused element
+    const focusTarget = target.hasAttribute("data-focusable")
+        ? target : document.body;
+    assert_equals(document.activeElement, focusTarget, "Focused right element");
+
+    // Check caret
+    const caretTarget = target.dataset.caretTarget
+        ? document.getElementById(target.dataset.caretTarget)
+        : target;
+    assert_equals(selection.anchorNode, caretTarget.firstChild, "Received caret");
+    assert_equals(selection.anchorOffset, 0, "Caret at position 0");
+    assert_equals(selection.isCollapsed, true, "Selection is collapsed");
+  }, target.id);
+}
+add_completion_callback(async () => {
+  // Scroll to log and remove hash from URL
+  await setHash("log");
+  history.pushState(null, "", " ");
+});
+</script>