Remove noisy error log for failing to find font fallback

Receiving a return value |false| in WebSandboxSupportLinux does not
allow discerning whether there was an internal failure to retrieve a
fallback font or just no fallback font was found which is more likely
and frequent to happen. Stop logging this situation, as it spams the
error log output.

Bug: 1005508
Change-Id: Id7447b42b717b508721d01a1287a498b7a4ea404
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1831865
Auto-Submit: Dominik Röttsches <drott@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#701241}

content/child/child_process_sandbox_support_impl_linux.cc

@@ -47,10 +47,8 @@ void WebSandboxSupportLinux::GetFallbackFontForCharacter(
   std::string family_name;
   if (!font_loader_->FallbackFontForCharacter(character, preferred_locale,
                                               &font_identity, &family_name,
-                                              &is_bold, &is_italic)) {
-    LOG(ERROR) << "FontService fallback request does not receive a response.";
+                                              &is_bold, &is_italic))
     return;
-  }
 
   // TODO(drott): Perhaps take OutOfProcessFont out of the picture here and pass
   // mojo FontIdentityPtr directly?