Prevent further uses of old downcast helpers

Type casting related functions like IsHTMLXXXXElement,
ToHTMLXXXXElement, and ToHTMLXXXXElementOrNull are being phased out in
favor of new downcast helpers in t_p/blink/renderer/platform/casting.h.
There is still a long run to fully remove old type casting mechanism,
but this CL aims at preventing new uses to take place.

Bug: 891908
Change-Id: I6a079b9524d2e94805528bdcf17baaa66fe091da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879628Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Abhijeet Kandalkar <abhijeet@igalia.com>
Cr-Commit-Position: refs/heads/master@{#710345}

PRESUBMIT.py

@@ -1074,6 +1074,33 @@ _BANNED_CPP_FUNCTIONS = (
         r'^third_party/blink/renderer/.*\.(cc|h)$',
       ),
     ),
+    (
+      r'/\bIsHTML.+Element\(\b',
+      (
+        'Function IsHTMLXXXXElement is deprecated. Instead, use downcast ',
+        ' helpers IsA<HTMLXXXXElement> from ',
+        '//third_party/blink/renderer/platform/casting.h.'
+      ),
+      False,
+      (
+        r'^third_party/blink/renderer/.*\.(cc|h)$',
+      ),
+    ),
+    (
+      r'/\bToHTML.+Element(|OrNull)\(\b',
+      (
+        'Function ToHTMLXXXXElement and ToHTMLXXXXElementOrNull are '
+        'deprecated. Instead, use downcast helpers To<HTMLXXXXElement> '
+        'and DynamicTo<HTMLXXXXElement> from ',
+        '//third_party/blink/renderer/platform/casting.h.'
+        'auto* html_xxxx_ele = To<HTMLXXXXElement>(n)'
+        'auto* html_xxxx_ele_or_null = DynamicTo<HTMLXXXXElement>(n)'
+      ),
+      False,
+      (
+        r'^third_party/blink/renderer/.*\.(cc|h)$',
+      ),
+    ),
     (
       r'/\bmojo::DataPipe\b',
       (

PRESUBMIT_test.py

@@ -1932,6 +1932,38 @@ class BannedTypeCheckTest(unittest.TestCase):
     self.assertTrue('some/cpp/problematic/file.c' in errors[0].message)
     self.assertTrue('some/cpp/ok/file.cc' not in errors[0].message)
 
+  def testBannedBlinkDowncastHelpers(self):
+    input_api = MockInputApi()
+    input_api.files = [
+      MockFile('some/cpp/problematic/file1.cc',
+               ['DEFINE_TYPE_CASTS(ToType, FromType, from_argument,'
+                'PointerPredicate(), ReferencePredicate());']),
+      MockFile('some/cpp/problematic/file2.cc',
+               ['bool is_test_ele = IsHTMLTestElement(n);']),
+      MockFile('some/cpp/problematic/file3.cc',
+               ['auto* html_test_ele = ToHTMLTestElement(n);']),
+      MockFile('some/cpp/problematic/file4.cc',
+               ['auto* html_test_ele_or_null = ToHTMLTestElementOrNull(n);']),
+      MockFile('some/cpp/ok/file1.cc',
+               ['bool is_test_ele = IsA<HTMLTestElement>(n);']),
+      MockFile('some/cpp/ok/file2.cc',
+               ['auto* html_test_ele = To<HTMLTestElement>(n);']),
+      MockFile('some/cpp/ok/file3.cc',
+               ['auto* html_test_ele_or_null = ',
+                'DynamicTo<HTMLTestElement>(n);']),
+    ]
+
+    # warnings are errors[0], errors are errors[1]
+    errors = PRESUBMIT._CheckNoBannedFunctions(input_api, MockOutputApi())
+    self.assertEqual(2, len(errors))
+    self.assertTrue('some/cpp/problematic/file1.cc' in errors[1].message)
+    self.assertTrue('some/cpp/problematic/file2.cc' in errors[0].message)
+    self.assertTrue('some/cpp/problematic/file3.cc' in errors[0].message)
+    self.assertTrue('some/cpp/problematic/file4.cc' in errors[0].message)
+    self.assertTrue('some/cpp/ok/file1.cc' not in errors[0].message)
+    self.assertTrue('some/cpp/ok/file2.cc' not in errors[0].message)
+    self.assertTrue('some/cpp/ok/file3.cc' not in errors[0].message)
+
   def testBannedIosObjcFunctions(self):
     input_api = MockInputApi()
     input_api.files = [