Enable highlight flag in PDFExtensionAccessibilityTextExtractionTest

The CL enables highlight feature flag kAccessiblePDFHighlight in
PDFExtensionAccessibilityTextExtractionTest. The CL updates the test
expectation file as well.

Bug: 1008775
Change-Id: Ic09596e920e409d4c2290092317bde1510571bba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2035491Reviewed-by: Kevin Babbitt <kbabbitt@microsoft.com>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Ankit Kumar 🌪️ <ankk@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#738455}

chrome/browser/pdf/pdf_extension_test.cc

@@ -2335,6 +2335,12 @@ class PDFExtensionAccessibilityTextExtractionTest : public PDFExtensionTest {
   PDFExtensionAccessibilityTextExtractionTest() = default;
   ~PDFExtensionAccessibilityTextExtractionTest() override = default;
 
+  void SetUpCommandLine(base::CommandLine* command_line) override {
+    PDFExtensionTest::SetUpCommandLine(command_line);
+    feature_list_.InitAndEnableFeature(
+        chrome_pdf::features::kAccessiblePDFHighlight);
+  }
+
   void RunTextExtractionTest(const base::FilePath::CharType* pdf_file) {
     base::FilePath test_path = ui_test_utils::GetTestFilePath(
         base::FilePath(FILE_PATH_LITERAL("pdf")),
@@ -2449,6 +2455,8 @@ class PDFExtensionAccessibilityTextExtractionTest : public PDFExtensionTest {
       lines.push_back(line);
     return lines;
   }
+
+  base::test::ScopedFeatureList feature_list_;
 };
 
 // Test that Previous/NextOnLineId attributes are present and properly linked on

chrome/test/data/pdf/accessibility/highlights-expected.txt

-Hello, nice meeting you
-
+Hello
+¶
+, nice 
+¶
+meeting
+¶
+ y
+¶
+ou
\ No newline at end of file