Fix captive portal histogram in SSL interstitials.

The SSL interstitial currently records captive portal histograms in its
constructor, but captive portal detection results arrive after the
interstitial is displayed so the histograms are incomplete.
This CL moves the histogram recording to the interstitial's destructor.


Review URL:

Cr-Commit-Position: refs/heads/master@{#316018}
3 files changed