Rename PasswordGenerationManager to PasswordGenerationFrameHelper.

The class isn't managing anything. It's stateless and just a set of utilities.
Additionally rename GenerationState to GenerationUIState because it's in the UI code.

Bug: 936011
Change-Id: If64c98344c1e74781dc403ddb907fdd2b92f308f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1520682
Commit-Queue: Vasilii Sukhanov <vasilii@chromium.org>
Reviewed-by: Vadym Doroshenko <dvadym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#640747}
28 files changed