PlzNavigate: set browser_initiated based on the NavigationEntry

This CL ensures that NavigatioRequest::browser_initiated_ will be set
based on the NavigationEntry provided. Currently, all NavigationRequest
created following a call to Navigator:;LoadEntry are marked as
browser-initiated, but they could be renderer-initiated instead.

BUG=

Review-Url: https://codereview.chromium.org/2567253005
Cr-Commit-Position: refs/heads/master@{#440637}
4 files changed