wait for ack from browser setting request headers

guessing this might fix the issue where some requests are missing the
warcprox-meta header, which results in their being written to the wrong
warc

brozzler/browser.py

@@ -495,12 +495,15 @@ class Browser:
     def configure_browser(self, extra_headers=None, user_agent=None):
         headers = extra_headers or {}
         headers['Accept-Encoding'] = 'gzip'  # avoid encodings br, sdch
-        self.send_to_chrome(
+        self.websock_thread.expect_result(self._command_id.peek())
+        msg_id = self.send_to_chrome(
                 method='Network.setExtraHTTPHeaders',
                 params={'headers': headers})
-
+        self._wait_for(
+                lambda: self.websock_thread.received_result(msg_id),
+                timeout=10)
         if user_agent:
-            self.send_to_chrome(
+            msg_id = self.send_to_chrome(
                     method='Network.setUserAgentOverride',
                     params={'userAgent': user_agent})
 

setup.py

@@ -32,7 +32,7 @@ def find_package_data(package):
 
 setuptools.setup(
         name='brozzler',
-        version='1.1b12.dev274',
+        version='1.1b12.dev275',
         description='Distributed web crawling with browsers',
         url='https://github.com/internetarchive/brozzler',
         author='Noah Levitt',