Deprecate --gfe2_reloadable_flag_always_use_strict_header_names.

PiperOrigin-RevId: 444316025
diff --git a/quiche/common/balsa/balsa_frame.cc b/quiche/common/balsa/balsa_frame.cc
index 7eecb7a..c50e16d 100644
--- a/quiche/common/balsa/balsa_frame.cc
+++ b/quiche/common/balsa/balsa_frame.cc
@@ -319,8 +319,8 @@
   const char* stream_begin = headers->OriginalHeaderStreamBegin();
   // The last line is always just a newline (and is uninteresting).
   const Lines::size_type lines_size_m1 = lines.size() - 1;
-  // For a trailer, there is no first line, so lines[0] is the first header
-  // . For real headers, the first line takes lines[0], so real header starts
+  // For a trailer, there is no first line, so lines[0] is the first header.
+  // For real headers, the first line takes lines[0], so real header starts
   // at index 1.
   int first_header_idx = (is_trailer ? 0 : 1);
   const char* current = stream_begin + lines[first_header_idx].first;
@@ -408,8 +408,7 @@
         break;
       }
 
-      if (http_validation_policy().enforce_header_characters() &&
-          IsInvalidHeaderKeyChar(*current)) {
+      if (IsInvalidHeaderKeyChar(*current)) {
         // Generally invalid characters were found earlier.
         HandleError(is_trailer
                         ? BalsaFrameEnums::INVALID_TRAILER_NAME_CHARACTER
diff --git a/quiche/common/balsa/http_validation_policy.cc b/quiche/common/balsa/http_validation_policy.cc
index b0418ec..4d44efa 100644
--- a/quiche/common/balsa/http_validation_policy.cc
+++ b/quiche/common/balsa/http_validation_policy.cc
@@ -10,21 +10,15 @@
 
 namespace quiche {
 
-HttpValidationPolicy::HttpValidationPolicy(bool enforce_header_keys,
-                                           bool enforce_all)
-    : enforce_header_keys_(enforce_header_keys), enforce_all_(enforce_all) {
-  if (enforce_all_) {
-    QUICHE_DCHECK(enforce_header_keys_);
-  }
-}
+HttpValidationPolicy::HttpValidationPolicy(bool enforce_all)
+    : enforce_all_(enforce_all) {}
 
 HttpValidationPolicy HttpValidationPolicy::CreateDefault() {
-  return HttpValidationPolicy(true, false);
+  return HttpValidationPolicy(false);
 }
 
 bool HttpValidationPolicy::operator==(const HttpValidationPolicy& other) const {
-  return std::tie(enforce_header_keys_, enforce_all_) ==
-         std::tie(other.enforce_header_keys_, other.enforce_all_);
+  return enforce_all_ == other.enforce_all_;
 }
 
 }  // namespace quiche
diff --git a/quiche/common/balsa/http_validation_policy.h b/quiche/common/balsa/http_validation_policy.h
index 3b75ec7..a98a08b 100644
--- a/quiche/common/balsa/http_validation_policy.h
+++ b/quiche/common/balsa/http_validation_policy.h
@@ -16,13 +16,10 @@
 // during the parsing of an HTTP request.
 class QUICHE_EXPORT_PRIVATE HttpValidationPolicy {
  public:
-  HttpValidationPolicy(bool enforce_header_keys, bool enforce_all);
+  HttpValidationPolicy(bool enforce_all);
 
   static HttpValidationPolicy CreateDefault();
 
-  // A header name has to be drawn from a set of allowed characters.
-  bool enforce_header_characters() const { return enforce_header_keys_; }
-
   // https://tools.ietf.org/html/rfc7230#section-3.2.4 deprecates "folding"
   // of long header lines onto continuation lines.
   bool disallow_header_continuation_lines() const { return enforce_all_; }
@@ -44,15 +41,11 @@
 
   friend QUICHE_EXPORT_PRIVATE std::ostream& operator<<(
       std::ostream& os, const HttpValidationPolicy& policy) {
-    os << "HttpValidationPolicy(enforce_header_keys_="
-       << policy.enforce_header_keys_
-       << ", enforce_all_=" << policy.enforce_all_ << ")";
+    os << "HttpValidationPolicy(enforce_all_=" << policy.enforce_all_ << ")";
     return os;
   }
 
  private:
-  // Enforce more standard-compliant parsing of HTTP headers.
-  bool enforce_header_keys_;
   // Enforce "everything": set for strictest possible parsing.
   bool enforce_all_;
 };