Add check for mismatching item and document sequence numbers.

Add check for mismatching item and document sequence numbers.

When a PageState update is received from the renderer process, it must
be for the current session history entry. This means that the sequence
numbers associated with the FrameNavigationEntry should match the ones
coming from the renderer process.
This CL adds a check for this case and drops the update if mismatch is
found.

BUG=628677
Review-Url: https://codereview.chromium.org/2196623003
Cr-Commit-Position: refs/heads/master@{#408698}
(cherry picked from commit 3463467767b4dbd5b0e52a1a0001cd6fb8288be4)

Committed: https://chromium.googlesource.com/chromium/src/+/f38836976725d366dbd0fb08054bea04f632ac59

[nasko, 2016-08-12 23:25:57]

Description was changed from

==========
Add check for mismatching item and document sequence numbers.

When a PageState update is received from the renderer process, it must
be for the current session history entry. This means that the sequence
numbers associated with the FrameNavigationEntry should match the ones
coming from the renderer process.
This CL adds a check for this case and drops the update if mismatch is
found.

BUG=628677

Review-Url: https://codereview.chromium.org/2196623003
Cr-Commit-Position: refs/heads/master@{#408698}
(cherry picked from commit 3463467767b4dbd5b0e52a1a0001cd6fb8288be4)
==========

to

==========
Add check for mismatching item and document sequence numbers.

When a PageState update is received from the renderer process, it must
be for the current session history entry. This means that the sequence
numbers associated with the FrameNavigationEntry should match the ones
coming from the renderer process.
This CL adds a check for this case and drops the update if mismatch is
found.

BUG=628677

Review-Url: https://codereview.chromium.org/2196623003
Cr-Commit-Position: refs/heads/master@{#408698}
(cherry picked from commit 3463467767b4dbd5b0e52a1a0001cd6fb8288be4)

Committed:
https://chromium.googlesource.com/chromium/src/+/f38836976725d366dbd0fb08054b...
==========

[nasko, 2016-08-12 23:25:59]

Committed patchset #1 (id:1) manually as
f38836976725d366dbd0fb08054bea04f632ac59.