Fix Huffman tree construction.

Fix Huffman tree construction.

HuffmanBuilder::ToVector() requires that there are at least 2 values
in the tree to create the array representation. This CL updates
HuffmanBuilder::BuildTree() to ensure it always returns a tree containing
at least 2 values.

Also demotes 2 CHECKs to DCHECKs because failure to align with the style guide
as failure does not constitute a security issue and enforces the requirement that
characters should not be larger than 127.

BUG=595493
Review-Url: https://codereview.chromium.org/2694363003
Cr-Commit-Position: refs/heads/master@{#450910}
Committed: https://chromium.googlesource.com/chromium/src/+/af126ad510eb5f6ba94fa96ef44bb49a576eaff6

[martijnc, 2017-02-15 20:20:55]

Description was changed from

==========
Fix Huffman tree construction.

BUG=595493
==========

to

==========
Fix Huffman tree construction.

HuffmanBuilder::ToVector() requires that there are at least 2 values
in the tree to create the array representation. This CL updates
HuffmanBuilder::BuildTree() to ensure it always returns a tree containing
at least 2 values.

Also demotes 2 CHECKs to DCHECKs because failure to align with the style guide
as failure does not constitute a security issue and enforces the requirement
that
characters should not be larger than 127.

BUG=595493
==========

[martijnc, 2017-02-15 20:20:55]

martijn@martijnc.be changed reviewers:
+ rsleevi@chromium.org

[martijnc, 2017-02-15 20:23:05]

Patchset #1 (id:1) has been deleted

[martijnc, 2017-02-15 22:09:09]

This is split off from https://codereview.chromium.org/2681733008.

https://codereview.chromium.org/2694363003/diff/20001/net/tools/transport_sec...
File net/tools/transport_security_state_generator/huffman/huffman_builder.cc
(left):

https://codereview.chromium.org/2694363003/diff/20001/net/tools/transport_sec...
net/tools/transport_security_state_generator/huffman/huffman_builder.cc:125: if
(item.second > 0) {
This check is always true.

Only RecordUsage() writes to |counts_| and only increments the value. If a
character is never used it won't be in |counts_| so the code wouldn't iterate
over it. If a character is used, its count would be 1 or higher.

[Ryan Sleevi, 2017-02-16 01:40:04]

lgtm

[martijnc, 2017-02-16 08:40:55]

The CQ bit was checked by martijn@martijnc.be

[commit-bot: I haz the power, 2017-02-16 08:41:40]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-02-16 09:13:35]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1487234455758210,
"parent_rev": "b05e107a3d28faf33ee6a3f4fc39aa4b560dc62e", "commit_rev":
"af126ad510eb5f6ba94fa96ef44bb49a576eaff6"}

[commit-bot: I haz the power, 2017-02-16 09:14:18]

Description was changed from

==========
Fix Huffman tree construction.

HuffmanBuilder::ToVector() requires that there are at least 2 values
in the tree to create the array representation. This CL updates
HuffmanBuilder::BuildTree() to ensure it always returns a tree containing
at least 2 values.

Also demotes 2 CHECKs to DCHECKs because failure to align with the style guide
as failure does not constitute a security issue and enforces the requirement
that
characters should not be larger than 127.

BUG=595493
==========

to

==========
Fix Huffman tree construction.

HuffmanBuilder::ToVector() requires that there are at least 2 values
in the tree to create the array representation. This CL updates
HuffmanBuilder::BuildTree() to ensure it always returns a tree containing
at least 2 values.

Also demotes 2 CHECKs to DCHECKs because failure to align with the style guide
as failure does not constitute a security issue and enforces the requirement
that
characters should not be larger than 127.

BUG=595493

Review-Url: https://codereview.chromium.org/2694363003
Cr-Commit-Position: refs/heads/master@{#450910}
Committed:
https://chromium.googlesource.com/chromium/src/+/af126ad510eb5f6ba94fa96ef44b...
==========

[commit-bot: I haz the power, 2017-02-16 09:14:19]

Committed patchset #1 (id:20001) as
https://chromium.googlesource.com/chromium/src/+/af126ad510eb5f6ba94fa96ef44b...