Add the precise-width integer check in cpp.py

Add a PRESUBMIT check to ensure new |unsigned short| use don't
come in.

Bug: 929986
Change-Id: Ib4031362495ceedd94bc7e33fcbb913aea1e6ee2
Reviewed-on: https://chromium-review.googlesource.com/c/1493642Reviewed-by: Kent Tamura <tkent@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Darwin Huang <huangdarwin@chromium.org>
Commit-Queue: Miyoung Shin <myid.shin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636674}

third_party/blink/tools/blinkpy/style/checkers/cpp.py

@@ -1865,6 +1865,13 @@ def check_language(filename, clean_lines, line_number, file_extension, include_s
 
     # FIXME: figure out if they're using default arguments in fn proto.
 
+    # Check if they're using a precise-width integer type.
+    matched = search(r'\bunsigned short\b', line)
+    if matched:
+        error(line_number, 'runtime/int', 1,
+              'Use a precise-width integer type from <stdint.h> or <cstdint>'
+              ' such as uint16_t instead of unsigned short')
+
     # Check to see if they're using an conversion function cast.
     # I just try to capture the most common basic types, though there are more.
     # Parameterless conversion functions, such as bool(), are allowed as they are
@@ -2623,6 +2630,7 @@ class CppChecker(object):
         'runtime/casting',
         'runtime/ctype_function',
         'runtime/explicit',
+        'runtime/int',
         'runtime/invalid_increment',
         'runtime/max_min_macros',
         'runtime/memset',

third_party/blink/tools/blinkpy/style/checkers/cpp_unittest.py

@@ -456,6 +456,13 @@ class CppStyleTest(CppStyleTestBase):
         self.assertEqual(cpp_style.Position(1, 1), cpp_style.close_expression(['}{}{', '}'], cpp_style.Position(0, 3)))
         self.assertEqual(cpp_style.Position(2, -1), cpp_style.close_expression(['][][', ' '], cpp_style.Position(0, 3)))
 
+    # Test the integer type.
+    def test_precise_width_integer(self):
+        self.assert_lint(
+            'unsigned short a = 1',
+            'Use a precise-width integer type from <stdint.h> or <cstdint> such as uint16_t instead of unsigned short'
+            '  [runtime/int] [1]')
+
     # Test C-style cast cases.
     def test_cstyle_cast(self):
         self.assert_lint(