win: Fix implicit conversion changes signedness error

patch/patch.cfg

@@ -649,5 +649,11 @@ patches = [
     # mac: Fix NOTREACHED with ViewsTextfieldTest.TextfieldKeyEvent.
     # https://bugs.chromium.org/p/chromium/issues/detail?id=1467329
     'name': 'mac_keyboard_conversion_1467329'
+  },
+  {
+    # win: Fix implicit conversion changes signedness error with
+    # cef_sandbox build.
+    # https://chromium-review.googlesource.com/c/chromium/src/+/4718245
+    'name': 'base_escape_4718245'
   }
 ]

patch/patches/base_escape_4718245.patch

@@ -0,0 +1,14 @@
+diff --git base/strings/escape.cc base/strings/escape.cc
+index d303ead90bc7d..d03da4c2ef2f6 100644
+--- base/strings/escape.cc
++++ base/strings/escape.cc
+@@ -443,8 +443,7 @@ std::string UnescapeURLWithAdjustmentsImpl(
+     if (!ShouldUnescapeCodePoint(rules, code_point)) {
+       // If it's a valid UTF-8 character, but not safe to unescape, copy all
+       // bytes directly.
+-      result.append(escaped_text.begin() + i,
+-                    escaped_text.begin() + i + 3 * unescaped.length());
++      result.append(escaped_text.substr(i, 3 * unescaped.length()));
+       i += unescaped.length() * 3;
+       continue;
+     }