[Password Generation] Use canonical version of action in for form matching in PasswordGenerationAgent

Even if the server found a suitable form for generation, Chrome will not show generation popup because form matching failed (e.g. if one action is canonical, another isn't).

This fix is temporary solution. This CL (https://codereview.chromium.org/2318533002) will use signature based matching.

BUG=582434

Review-Url: https://codereview.chromium.org/2320563002
Cr-Commit-Position: refs/heads/master@{#416932}
5 files changed