Skip page refresh navigation in navigation observer

Skip page refresh navigation in navigation observer

Since page refresh navigations have the same source and destination url,
and do not help us attribute downloads, we can safely skip them (and
save the quota for other meaningful navigations).

BUG=698121
Review-Url: https://codereview.chromium.org/2728123003
Cr-Commit-Position: refs/heads/master@{#454658}
(cherry picked from commit 0a5231e4ca6ec1af9908e4b35590da1cdf4918fa)

Review-Url: https://codereview.chromium.org/2734913002 .
Cr-Commit-Position: refs/branch-heads/2987@{#771}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed: https://chromium.googlesource.com/chromium/src/+/f9336d16c03b81831b6e547a005a3dfd06b65450

[Jialiu Lin, 2017-03-06 18:45:52]

Description was changed from

==========
Skip page refresh navigation in navigation observer

Since page refresh navigations have the same source and destination url,
and do not help us attribute downloads, we can safely skip them (and
save the quota for other meaningful navigations).

BUG=698121

Review-Url: https://codereview.chromium.org/2728123003
Cr-Commit-Position: refs/heads/master@{#454658}
(cherry picked from commit 0a5231e4ca6ec1af9908e4b35590da1cdf4918fa)
==========

to

==========
Skip page refresh navigation in navigation observer

Since page refresh navigations have the same source and destination url,
and do not help us attribute downloads, we can safely skip them (and
save the quota for other meaningful navigations).

BUG=698121

Review-Url: https://codereview.chromium.org/2728123003
Cr-Commit-Position: refs/heads/master@{#454658}
(cherry picked from commit 0a5231e4ca6ec1af9908e4b35590da1cdf4918fa)

Review-Url: https://codereview.chromium.org/2734913002 .
Cr-Commit-Position: refs/branch-heads/2987@{#771}
Cr-Branched-From:
ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed:
https://chromium.googlesource.com/chromium/src/+/f9336d16c03b81831b6e547a005a...
==========

[Jialiu Lin, 2017-03-06 18:45:53]

Committed patchset #1 (id:1) manually as
f9336d16c03b81831b6e547a005a3dfd06b65450.