Fixes the top 500 keywords generation to split keywords on "-".

Initially, the keywords generation algorithm would not split the input
URLs on "-", creating a conflict with the sensitive keywords search
heuristic (which does split on "-"). This CL remedies that, by ensuring
that keywords are split on "-" before being put into the keywords list.

Bug: 1015843
Change-Id: Iad3127788f4fd363a9ff7817ef55072c07768a02
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1869119Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Commit-Queue: Aidan Beggs <beggs@google.com>
Cr-Commit-Position: refs/heads/master@{#707476}

components/url_formatter/spoof_checks/top_domains/make_top_domain_list_variables.cc

@@ -130,14 +130,23 @@ int main(int argc, char* argv[]) {
     }
 
     if (keywords.size() < kTopN) {
-      std::string keyword;
+      std::string keywords_for_current_line;
       base::TrimString(
           url_formatter::top_domains::HostnameWithoutRegistry(line), ".",
-          &keyword);
-      CHECK(keyword.find('.') == std::string::npos);
+          &keywords_for_current_line);
+      CHECK(keywords_for_current_line.find('.') == std::string::npos);
+
+      for (const std::string& keyword : base::SplitString(
+               keywords_for_current_line, "-", base::TRIM_WHITESPACE,
+               base::SPLIT_WANT_NONEMPTY)) {
         if (keywords.find(keyword) == keywords.end()) {
           keywords.insert(keyword);
         }
+
+        if (keywords.size() >= kTopN) {
+          break;
+        }
+      }
     }
   }