Add IsInitialBlankNavigation to detect new tabs that aren't clones.
Once we create a NavigationEntry for the initial blank page, it won't
be safe to check GetEntryCount() == 0 to detect newly created tabs.
IsInitialNavigation is close, but it returns true for cloned tabs as
well, which is different. (For example, we want to be able to restore
cloned tabs that haven't committed, but not new blank tabs.)
Places that check GetEntryCount() == 0 should use the new
IsInitialBlankNavigation instead.
BUG=524208
TEST=Duplicate a tab, close it before its first commit, and restore it.
Review URL: https://codereview.chromium.org/1395353003
Cr-Commit-Position: refs/heads/master@{#353776}
18 files changed
