Move ~200 Feature objects to read-only memory in Windows builds

Move ~200 Feature objects to read-only memory in Windows builds

A VC++ bug was preventing base::Feature objects from going into the
read-only section despite being tagged as const. Adding a constexpr
constructor solves this problem. Some of the variables (kTimerThrottlingForHiddenFrames for instance) get optimized away
entirely which is why the size changes are not symmetrical.

The VC++ bug is:
https://connect.microsoft.com/VisualStudio/feedback/details/3117602

Previous instances of this bug were worked around by deleting const
but this seemed undesirable in this case. Luckily the constexpr fix
seems to work just as well.

Approximate deltas are:

chrome.dll
       .text:     -48 bytes change
      .rdata:    1216 bytes change
       .data:   -1376 bytes change
      .reloc:     -32 bytes change
Total change:    -240 bytes

chrome_child.dll
       .text:     -16 bytes change
      .rdata:     704 bytes change
       .data:    -800 bytes change
      .reloc:      32 bytes change
Total change:     -80 bytes

Modest, but it's good to move a few hundred variables to read-only
memory.

This should not affect other platforms.

BUG=677351
Review-Url: https://codereview.chromium.org/2623373004
Cr-Commit-Position: refs/heads/master@{#443616}
Committed: https://chromium.googlesource.com/chromium/src/+/cbbcb90c9c4388226eadba1632bc85040e66c8cc

[brucedawson, 2017-01-12 23:01:20]

The CQ bit was checked by brucedawson@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-01-12 23:03:10]

Dry run: 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, 2017-01-13 00:26:46]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-01-13 00:26:46]

Dry run: This issue passed the CQ dry run.

[brucedawson, 2017-01-13 01:16:40]

Description was changed from

==========
Move ~100 Feature objects to read-only memory in Windows builds

A VC++ bug was preventing base::Feature objects from going into the
read-only section despite being tagged as const. Adding a constexpr
constructor solves this problem, removing -1376 bytes from the
read/write data segment and adding 1216 bytes to the read-only data
segment. Some of the variables (kTimerThrottlingForHiddenFrames for
instance) get optimized away entirely which is why the size changes
are not symmetrical.

The VC++ bug is:
https://connect.microsoft.com/VisualStudio/feedback/details/3117602

Previous instances of this bug were worked around by deleting const
but this seemed undesirable in this case. Luckily the constexpr fix
seems to work just as well.

This should not affect other platforms.

BUG=677351
==========

to

==========
Move ~100 Feature objects to read-only memory in Windows builds

A VC++ bug was preventing base::Feature objects from going into the
read-only section despite being tagged as const. Adding a constexpr
constructor solves this problem. Some of the variables
(kTimerThrottlingForHiddenFrames for instance) get optimized away
entirely which is why the size changes are not symmetrical.

The VC++ bug is:
https://connect.microsoft.com/VisualStudio/feedback/details/3117602

Previous instances of this bug were worked around by deleting const
but this seemed undesirable in this case. Luckily the constexpr fix
seems to work just as well.

Approximate deltas are:

chrome.dll
       .text:     -48 bytes change
      .rdata:    1216 bytes change
       .data:   -1376 bytes change
      .reloc:     -32 bytes change
Total change:    -240 bytes

chrome_child.dll
       .text:     -16 bytes change
      .rdata:     704 bytes change
       .data:    -800 bytes change
      .reloc:      32 bytes change
Total change:     -80 bytes

Modest, but it's good to move a few hundred variables to read-only
memory.

This should not affect other platforms.

BUG=677351
==========

[brucedawson, 2017-01-13 01:16:41]

brucedawson@chromium.org changed reviewers:
+ dcheng@chromium.org

[brucedawson, 2017-01-13 01:17:43]

What do you think?

Not a big change but I don't think it has any disadvantages.

[brucedawson, 2017-01-13 01:17:56]

Description was changed from

==========
Move ~100 Feature objects to read-only memory in Windows builds

A VC++ bug was preventing base::Feature objects from going into the
read-only section despite being tagged as const. Adding a constexpr
constructor solves this problem. Some of the variables
(kTimerThrottlingForHiddenFrames for instance) get optimized away
entirely which is why the size changes are not symmetrical.

The VC++ bug is:
https://connect.microsoft.com/VisualStudio/feedback/details/3117602

Previous instances of this bug were worked around by deleting const
but this seemed undesirable in this case. Luckily the constexpr fix
seems to work just as well.

Approximate deltas are:

chrome.dll
       .text:     -48 bytes change
      .rdata:    1216 bytes change
       .data:   -1376 bytes change
      .reloc:     -32 bytes change
Total change:    -240 bytes

chrome_child.dll
       .text:     -16 bytes change
      .rdata:     704 bytes change
       .data:    -800 bytes change
      .reloc:      32 bytes change
Total change:     -80 bytes

Modest, but it's good to move a few hundred variables to read-only
memory.

This should not affect other platforms.

BUG=677351
==========

to

==========
Move ~200 Feature objects to read-only memory in Windows builds

A VC++ bug was preventing base::Feature objects from going into the
read-only section despite being tagged as const. Adding a constexpr
constructor solves this problem. Some of the variables
(kTimerThrottlingForHiddenFrames for instance) get optimized away
entirely which is why the size changes are not symmetrical.

The VC++ bug is:
https://connect.microsoft.com/VisualStudio/feedback/details/3117602

Previous instances of this bug were worked around by deleting const
but this seemed undesirable in this case. Luckily the constexpr fix
seems to work just as well.

Approximate deltas are:

chrome.dll
       .text:     -48 bytes change
      .rdata:    1216 bytes change
       .data:   -1376 bytes change
      .reloc:     -32 bytes change
Total change:    -240 bytes

chrome_child.dll
       .text:     -16 bytes change
      .rdata:     704 bytes change
       .data:    -800 bytes change
      .reloc:      32 bytes change
Total change:     -80 bytes

Modest, but it's good to move a few hundred variables to read-only
memory.

This should not affect other platforms.

BUG=677351
==========

[dcheng, 2017-01-13 09:17:08]

On 2017/01/13 01:17:43, brucedawson wrote:
> What do you think?
> 
> Not a big change but I don't think it has any disadvantages.

LGTM. Doesn't seem to hurt, so why not?

[brucedawson, 2017-01-13 18:18:17]

The CQ bit was checked by brucedawson@chromium.org

[commit-bot: I haz the power, 2017-01-13 18:18:43]

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, 2017-01-13 18:24:41]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1484331497821140, "parent_rev":
"ea496fdbc84ee1a8aaa2c2fc8fb3b19546ddb996", "commit_rev":
"cbbcb90c9c4388226eadba1632bc85040e66c8cc"}

[commit-bot: I haz the power, 2017-01-13 18:25:16]

Description was changed from

==========
Move ~200 Feature objects to read-only memory in Windows builds

A VC++ bug was preventing base::Feature objects from going into the
read-only section despite being tagged as const. Adding a constexpr
constructor solves this problem. Some of the variables
(kTimerThrottlingForHiddenFrames for instance) get optimized away
entirely which is why the size changes are not symmetrical.

The VC++ bug is:
https://connect.microsoft.com/VisualStudio/feedback/details/3117602

Previous instances of this bug were worked around by deleting const
but this seemed undesirable in this case. Luckily the constexpr fix
seems to work just as well.

Approximate deltas are:

chrome.dll
       .text:     -48 bytes change
      .rdata:    1216 bytes change
       .data:   -1376 bytes change
      .reloc:     -32 bytes change
Total change:    -240 bytes

chrome_child.dll
       .text:     -16 bytes change
      .rdata:     704 bytes change
       .data:    -800 bytes change
      .reloc:      32 bytes change
Total change:     -80 bytes

Modest, but it's good to move a few hundred variables to read-only
memory.

This should not affect other platforms.

BUG=677351
==========

to

==========
Move ~200 Feature objects to read-only memory in Windows builds

A VC++ bug was preventing base::Feature objects from going into the
read-only section despite being tagged as const. Adding a constexpr
constructor solves this problem. Some of the variables
(kTimerThrottlingForHiddenFrames for instance) get optimized away
entirely which is why the size changes are not symmetrical.

The VC++ bug is:
https://connect.microsoft.com/VisualStudio/feedback/details/3117602

Previous instances of this bug were worked around by deleting const
but this seemed undesirable in this case. Luckily the constexpr fix
seems to work just as well.

Approximate deltas are:

chrome.dll
       .text:     -48 bytes change
      .rdata:    1216 bytes change
       .data:   -1376 bytes change
      .reloc:     -32 bytes change
Total change:    -240 bytes

chrome_child.dll
       .text:     -16 bytes change
      .rdata:     704 bytes change
       .data:    -800 bytes change
      .reloc:      32 bytes change
Total change:     -80 bytes

Modest, but it's good to move a few hundred variables to read-only
memory.

This should not affect other platforms.

BUG=677351

Review-Url: https://codereview.chromium.org/2623373004
Cr-Commit-Position: refs/heads/master@{#443616}
Committed:
https://chromium.googlesource.com/chromium/src/+/cbbcb90c9c4388226eadba1632bc...
==========

[commit-bot: I haz the power, 2017-01-13 18:25:17]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/cbbcb90c9c4388226eadba1632bc...