[Offline pages]: Move logic for whether to consider the DocumentAvailableInMainFrame signal to the …

[Offline pages]: Move logic for whether to consider the DocumentAvailableInMainFrame signal to the snapshot controller

Changes include:
-- moving all timing parameters (how long to wait before snapshotting) to the snapshot controller
-- introducing 2 new factory methods for obtaining a snapshot controller
-- more explicit ownership and transfer of the snapshot controller

BUG=712473
Review-Url: https://codereview.chromium.org/2822023002
Cr-Commit-Position: refs/heads/master@{#468765}
(cherry picked from commit 5e17a9358f03488e71cba7c4b6786afba95fed6e)

Review-Url: https://codereview.chromium.org/2861583007 .
Cr-Commit-Position: refs/branch-heads/3071@{#382}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed: https://chromium.googlesource.com/chromium/src/+/b7ff7afba5f6d89f8a9b29dd12c4a7d5d15fa655

[dewittj, 2017-05-03 20:42:23]

Description was changed from

==========
[Offline pages]: Move logic for whether to consider the
DocumentAvailableInMainFrame signal to the snapshot controller

Changes include:
-- moving all timing parameters (how long to wait before snapshotting) to the
snapshot controller
-- introducing 2 new factory methods for obtaining a snapshot controller
-- more explicit ownership and transfer of the snapshot controller

BUG=712473

Review-Url: https://codereview.chromium.org/2822023002
Cr-Commit-Position: refs/heads/master@{#468765}
(cherry picked from commit 5e17a9358f03488e71cba7c4b6786afba95fed6e)
==========

to

==========
[Offline pages]: Move logic for whether to consider the
DocumentAvailableInMainFrame signal to the snapshot controller

Changes include:
-- moving all timing parameters (how long to wait before snapshotting) to the
snapshot controller
-- introducing 2 new factory methods for obtaining a snapshot controller
-- more explicit ownership and transfer of the snapshot controller

BUG=712473

Review-Url: https://codereview.chromium.org/2822023002
Cr-Commit-Position: refs/heads/master@{#468765}
(cherry picked from commit 5e17a9358f03488e71cba7c4b6786afba95fed6e)

Review-Url: https://codereview.chromium.org/2861583007 .
Cr-Commit-Position: refs/branch-heads/3071@{#382}
Cr-Branched-From:
a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed:
https://chromium.googlesource.com/chromium/src/+/b7ff7afba5f6d89f8a9b29dd12c4...
==========

[dewittj, 2017-05-03 20:42:24]

Committed patchset #1 (id:1) manually as
b7ff7afba5f6d89f8a9b29dd12c4a7d5d15fa655.