Remove DCHECK asserting fonts registry keys are returned

Remove DCHECK(it.ValueCount()); as this appears flaky on the Win 7 dbg
bot and RegistryValueIterator does occasionally not return
values. Remove this DCHECK as the test is restarted anyway in each run
on the bots and the DCHECK is not essential to ensuring that
DWriteFontLookupTableBuilder runs and indexes fonts.

Bug: 1065344, 1066801
Change-Id: I95f45c55ab9342512af6becfe7d4c8074d1c186b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2130854Reviewed-by: Anatoliy Potapchuk <apotapchuk@chromium.org>
Commit-Queue: Dominik Röttsches <drott@chromium.org>
Cr-Commit-Position: refs/heads/master@{#755318}

content/browser/renderer_host/dwrite_font_lookup_table_builder_win.cc

@@ -211,7 +211,6 @@ std::string DWriteFontLookupTableBuilder::ComputePersistenceHash() {
   const wchar_t kFonts[] =
       L"Software\\Microsoft\\Windows NT\\CurrentVersion\\Fonts";
   base::win::RegistryValueIterator it(HKEY_LOCAL_MACHINE, kFonts);
-  DCHECK(it.ValueCount());
   for (; it.Valid(); ++it) {
     to_hash.append(base::WideToUTF8(it.Name()));
     to_hash.append(base::WideToUTF8(it.Value()));