Implement :~: fragment directive delimiter

Implement the newly proposed fragment directive delimiter :~:. This
delimiter behaves the same as the previously implemented ## delimiter,
but is valid by URL spec and thus should be a better option. For now,
both delimiters are supported, but the ## delimiter will be removed for
M79 once we confirm we want to use :~:.

Bug: 1007016
Change-Id: Icd732d27ccc3a7591617735afee9d14d5d1c68f1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1822512
Commit-Queue: David Bokan <bokan@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#699589}

third_party/blink/renderer/core/dom/document.cc

@@ -4533,26 +4533,43 @@ void Document::SetURL(const KURL& url) {
 
   // If text fragment identifiers are enabled, we strip the fragment directive
   // from the URL fragment.
-  // E.g. "#id##targetText=a" --> "#id"
+  // E.g. "#id:~:targetText=a" --> "#id"
   if (RuntimeEnabledFeatures::TextFragmentIdentifiersEnabled(this)) {
-    // Add a hash to the beginning of the fragment as it is part of parsing the
-    // ## fragment directive prefix but is not included in FragmentIdentifier().
-    String fragment = "#" + new_url.FragmentIdentifier();
+    String fragment = new_url.FragmentIdentifier();
+    wtf_size_t start_pos = fragment.Find(kFragmentDirectiveNewPrefix);
+    if (start_pos != kNotFound) {
+      fragment_directive_ = fragment.Substring(
+          start_pos + kFragmentDirectiveNewPrefixStringLength);
+
+      if (start_pos == 0)
+        new_url.RemoveFragmentIdentifier();
+      else
+        new_url.SetFragmentIdentifier(fragment.Substring(0, start_pos));
+    } else {
+      // TODO(crbug/1007016): Remove support for the old prefix, we currently
+      // fall back to checking ## if we did not find the new delimiter :~:.
+
+      // Add a hash to the beginning of the fragment as it is part of parsing
+      // the ## fragment directive prefix but is not included in
+      // FragmentIdentifier().
+      fragment = "#" + fragment;
       wtf_size_t start_pos = fragment.Find(kFragmentDirectivePrefix);
       if (start_pos != kNotFound) {
-      fragment_directive_ =
-          fragment.Substring(start_pos + kFragmentDirectivePrefixStringLength);
+        fragment_directive_ = fragment.Substring(
+            start_pos + kFragmentDirectivePrefixStringLength);
+
         if (start_pos == 0) {
           // Remove the URL fragment if it is entirely a fragment directive.
           new_url.RemoveFragmentIdentifier();
         } else {
-        // The stripped fragment starts at position 1 and has length start_pos-1
-        // due to the added hash.
+          // The stripped fragment starts at position 1 and has length
+          // start_pos-1 due to the added hash.
           String stripped_fragment = fragment.Substring(1, start_pos - 1);
           new_url.SetFragmentIdentifier(stripped_fragment);
         }
       }
     }
+  }
 
   url_ = new_url;
   access_entry_from_url_ = nullptr;

third_party/blink/renderer/core/page/scrolling/text_fragment_anchor.h

@@ -24,6 +24,12 @@ constexpr char kFragmentDirectivePrefix[] = "##";
 // Subtract 1 because base::size includes the \0 string terminator.
 constexpr size_t kFragmentDirectivePrefixStringLength =
     base::size(kFragmentDirectivePrefix) - 1;
+// TODO(crbug/1007016): Remove support for the old prefix once we confirm the
+// new prefix choice.
+constexpr char kFragmentDirectiveNewPrefix[] = ":~:";
+// Subtract 1 because base::size includes the \0 string terminator.
+constexpr size_t kFragmentDirectiveNewPrefixStringLength =
+    base::size(kFragmentDirectiveNewPrefix) - 1;
 
 enum class TextFragmentFormat { PlainFragment, FragmentDirective };
 

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

@@ -1562,6 +1562,105 @@ TEST_F(TextFragmentAnchorTest, DismissTextHighlightInView) {
   EXPECT_FALSE(GetDocument().View()->GetFragmentAnchor());
 }
 
+// Test that the fragment directive delimiter :~: works properly and is stripped
+// from the URL.
+TEST_F(TextFragmentAnchorTest, FragmentDirectiveDelimiter) {
+  SimRequest request("https://example.com/test.html#:~:targetText=test",
+                     "text/html");
+  LoadURL("https://example.com/test.html#:~:targetText=test");
+  request.Complete(R"HTML(
+    <!DOCTYPE html>
+    <style>
+      body {
+        height: 1200px;
+      }
+      p {
+        position: absolute;
+        top: 1000px;
+      }
+    </style>
+    <p id="text">This is a test page</p>
+  )HTML");
+  Compositor().BeginFrame();
+
+  RunAsyncMatchingTasks();
+
+  EXPECT_EQ(1u, GetDocument().Markers().Markers().size());
+
+  EXPECT_EQ(GetDocument().Url(), "https://example.com/test.html");
+}
+
+// Test that a :~: fragment directive is scrolled into view and is stripped from
+// the URL when there's also a valid element fragment.
+TEST_F(TextFragmentAnchorTest, FragmentDirectiveDelimiterWithElementFragment) {
+  SimRequest request("https://example.com/test.html#element:~:targetText=test",
+                     "text/html");
+  LoadURL("https://example.com/test.html#element:~:targetText=test");
+  request.Complete(R"HTML(
+    <!DOCTYPE html>
+    <style>
+      body {
+        height: 2200px;
+      }
+      #text {
+        position: absolute;
+        top: 1000px;
+      }
+      #element {
+        position: absolute;
+        top: 2000px;
+      }
+    </style>
+    <p id="text">This is a test page</p>
+    <div id="element">Some text</div>
+  )HTML");
+  Compositor().BeginFrame();
+
+  RunAsyncMatchingTasks();
+
+  EXPECT_EQ(GetDocument().Url(), "https://example.com/test.html#element");
+
+  Element& p = *GetDocument().getElementById("text");
+
+  EXPECT_TRUE(ViewportRect().Contains(BoundingRectInFrame(p)))
+      << "<p> Element wasn't scrolled into view, viewport's scroll offset: "
+      << LayoutViewport()->GetScrollOffset().ToString();
+}
+
+// Test that a fragment directive is stripped from the URL even if it is not a
+// targetText.
+TEST_F(TextFragmentAnchorTest, IdFragmentWithFragmentDirective) {
+  SimRequest request("https://example.com/test.html#element:~:id", "text/html");
+  LoadURL("https://example.com/test.html#element:~:id");
+  request.Complete(R"HTML(
+    <!DOCTYPE html>
+    <style>
+      body {
+        height: 2200px;
+      }
+      p {
+        position: absolute;
+        top: 1000px;
+      }
+      div {
+        position: absolute;
+        top: 2000px;
+      }
+    </style>
+    <p id="element">This is a test page</p>
+    <div id="element:~:id">Some text</div>
+  )HTML");
+  Compositor().BeginFrame();
+
+  RunAsyncMatchingTasks();
+
+  Element& div = *GetDocument().getElementById("element");
+
+  EXPECT_TRUE(ViewportRect().Contains(BoundingRectInFrame(div)))
+      << "Should have scrolled <div> into view but didn't, scroll offset: "
+      << LayoutViewport()->GetScrollOffset().ToString();
+}
+
 }  // namespace
 
 }  // namespace blink