Add exception in GLibLogHandler for Gtk theme warning

BUG=700117
TBR=boliu@chromium.org

Review-Url: https://codereview.chromium.org/2748443003
Cr-Commit-Position: refs/heads/master@{#456194}

content/browser/browser_main_loop.cc

@@ -277,6 +277,8 @@ static void GLibLogHandler(const gchar* log_domain,
     LOG(ERROR) << message;
   } else if (strstr(message, "Could not obtain desktop path or name")) {
     LOG(ERROR) << message;
+  } else if (strstr(message, "Theme parsing error")) {
+    LOG(ERROR) << message;
   } else {
     LOG(DFATAL) << log_domain << ": " << message;
   }