[Telemetry] Make page navigations synchronous.

This fixes a race where a stray Page.frameNavigated might be considered to be a
completion of the requested navigation.

Unfortunately, I don't know how to trigger this race in a unittest.

BUG=367306

Review URL: https://codereview.chromium.org/291033002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271655 0039d316-1c4b-4281-b951-d872f2087c98

tools/telemetry/telemetry/core/backends/chrome/inspector_page.py

@@ -101,19 +101,13 @@ class InspectorPage(object):
 
     def DoNavigate():
       self._SetScriptToEvaluateOnCommit(script_to_evaluate_on_commit)
-      # Navigate the page. However, there seems to be a bug in chrome devtools
-      # protocol where the request id for this event gets held on the browser
-      # side pretty much indefinitely.
-      #
-      # So, instead of waiting for the event to actually complete, wait for the
-      # Page.frameNavigated event.
       request = {
           'method': 'Page.navigate',
           'params': {
               'url': url,
               }
           }
-      self._inspector_backend.SendAndIgnoreResponse(request)
+      self._inspector_backend.SyncRequest(request, timeout)
     self._navigation_url = url
     self.PerformActionAndWaitForNavigate(DoNavigate, timeout)