Add HexToUint64 parsing for wtf_string

This adds a util to parse a hex string to uint64. This is necessary for
the ConversionMeasurement API, as the impression data attribute is a
64-bit identifier provided as a hex string.

Link to explainer:
https://github.com/WICG/conversion-measurement-api#impression-declaration

Usage of this is included on https://crrev.com/c/2012883 in
html_anchor_element.cc

Change-Id: I18aeef488477a83dbcb31351fd9179f4957f5f5a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2123811Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: John Delaney <johnidel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#754515}

third_party/blink/renderer/platform/wtf/text/string_impl.cc

@@ -701,6 +701,15 @@ wtf_size_t StringImpl::HexToUIntStrict(bool* ok) {
                              NumberParsingOptions::kStrict, ok);
 }
 
+uint64_t StringImpl::HexToUInt64Strict(bool* ok) {
+  if (Is8Bit()) {
+    return HexCharactersToUInt64(Characters8(), length_,
+                                 NumberParsingOptions::kStrict, ok);
+  }
+  return HexCharactersToUInt64(Characters16(), length_,
+                               NumberParsingOptions::kStrict, ok);
+}
+
 int64_t StringImpl::ToInt64(NumberParsingOptions options, bool* ok) const {
   if (Is8Bit())
     return CharactersToInt64(Characters8(), length_, options, ok);

third_party/blink/renderer/platform/wtf/text/string_impl.h

@@ -345,6 +345,7 @@ class WTF_EXPORT StringImpl {
   uint64_t ToUInt64(NumberParsingOptions, bool* ok) const;
 
   wtf_size_t HexToUIntStrict(bool* ok);
+  uint64_t HexToUInt64Strict(bool* ok);
 
   // FIXME: Like NumberParsingOptions::kStrict, these give false for "ok" when
   // there is trailing garbage.  Like NumberParsingOptions::kLoose, these return

third_party/blink/renderer/platform/wtf/text/string_to_number.cc

@@ -175,6 +175,20 @@ unsigned HexCharactersToUInt(const UChar* data,
   return ToIntegralType<unsigned, UChar, 16>(data, length, options, ok);
 }
 
+uint64_t HexCharactersToUInt64(const LChar* data,
+                               size_t length,
+                               NumberParsingOptions options,
+                               bool* ok) {
+  return ToIntegralType<uint64_t, LChar, 16>(data, length, options, ok);
+}
+
+uint64_t HexCharactersToUInt64(const UChar* data,
+                               size_t length,
+                               NumberParsingOptions options,
+                               bool* ok) {
+  return ToIntegralType<uint64_t, UChar, 16>(data, length, options, ok);
+}
+
 int CharactersToInt(const LChar* data,
                     size_t length,
                     NumberParsingOptions options,

third_party/blink/renderer/platform/wtf/text/string_to_number.h

@@ -40,6 +40,14 @@ WTF_EXPORT unsigned HexCharactersToUInt(const UChar*,
                                         size_t,
                                         NumberParsingOptions,
                                         bool* ok);
+WTF_EXPORT uint64_t HexCharactersToUInt64(const UChar*,
+                                          size_t,
+                                          NumberParsingOptions,
+                                          bool* ok);
+WTF_EXPORT uint64_t HexCharactersToUInt64(const LChar*,
+                                          size_t,
+                                          NumberParsingOptions,
+                                          bool* ok);
 WTF_EXPORT unsigned CharactersToUInt(const LChar*,
                                      size_t,
                                      NumberParsingOptions,

third_party/blink/renderer/platform/wtf/text/wtf_string.cc

@@ -295,6 +295,15 @@ unsigned String::HexToUIntStrict(bool* ok) const {
   return impl_->HexToUIntStrict(ok);
 }
 
+uint64_t String::HexToUInt64Strict(bool* ok) const {
+  if (!impl_) {
+    if (ok)
+      *ok = false;
+    return 0;
+  }
+  return impl_->HexToUInt64Strict(ok);
+}
+
 int64_t String::ToInt64Strict(bool* ok) const {
   if (!impl_) {
     if (ok)

third_party/blink/renderer/platform/wtf/text/wtf_string.h

@@ -422,6 +422,7 @@ class WTF_EXPORT String {
   int ToIntStrict(bool* ok = nullptr) const;
   unsigned ToUIntStrict(bool* ok = nullptr) const;
   unsigned HexToUIntStrict(bool* ok) const;
+  uint64_t HexToUInt64Strict(bool* ok) const;
   int64_t ToInt64Strict(bool* ok = nullptr) const;
   uint64_t ToUInt64Strict(bool* ok = nullptr) const;