This is a hard bug to reproduce, but some of our internal tests can repro it. See b/31024981 for context (Googlers only, sorry), but I've copied the important details into this bug.

The problem happens when the test clicks something which triggers a cross-process navigation to a page hosted on another domain. Frame ids  "697729.1", "697951.1" and "697951.4" start loading. We receive Page.frameStoppedLoading events for "697951.1" and "697951.4", but not "697729.1".

I think "697729.1" is from the old discarded renderer process. ChromeDriver should not wait for the Page.frameStoppedLoading event for this frame.

Here are the lines of interest from chromedriver.log:

[8.843][DEBUG]: DEVTOOLS EVENT Page.frameNavigated {
      "url": "<url from first domain>"
[10.587][INFO]: COMMAND ClickElement {
[10.683][DEBUG]: DEVTOOLS EVENT Page.frameStartedLoading {
   "frameId": "697729.1"
[11.427][DEBUG]: DEVTOOLS EVENT Page.frameStartedLoading {
   "frameId": "697951.1"
[11.555][DEBUG]: DEVTOOLS EVENT Page.frameNavigated {
      "id": "697951.1",
      "url": "<url from second domain>"
[11.682][DEBUG]: DEVTOOLS EVENT Page.frameAttached {
   "frameId": "697951.4",
   "parentFrameId": "697951.1"
[11.683][DEBUG]: DEVTOOLS EVENT Page.frameStartedLoading {
   "frameId": "697951.4"
[11.683][DEBUG]: DEVTOOLS EVENT Page.frameNavigated {
      "id": "697951.4",
      "securityOrigin": "<url from second domain>",
      "url": "about:blank"
[11.684][DEBUG]: DEVTOOLS EVENT Page.frameStoppedLoading {
   "frameId": "697951.4"
[12.809][DEBUG]: DEVTOOLS EVENT Page.frameStoppedLoading {
   "frameId": "697951.1"
[310.656][INFO]: RESPONSE ClickElement timeout: cannot determine loading status