Add utility method for WebString to base::FilePath conversion

Add utility method for WebString to base::FilePath conversion

Converting WebString to base::FilePath used to go through string16, but
- FilePath can take UTF8 depending on platforms (e.g. on posix), and
- We can use StringPiece to avoid extra string copy when possible

BUG=n/a

Committed: https://crrev.com/b473f003f012766b87c4a14672f924ea7cffaea5
Cr-Commit-Position: refs/heads/master@{#376688}

[kinuko, 2016-02-12 11:19:14]

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

[commit-bot: I haz the power, 2016-02-12 11:19:20]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/1

[commit-bot: I haz the power, 2016-02-12 11:47:41]

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

[commit-bot: I haz the power, 2016-02-12 11:47:42]

Dry run: Try jobs failed on following builders:
  cast_shell_linux on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/cast_shell_linu...)

[kinuko, 2016-02-14 07:16:05]

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

[commit-bot: I haz the power, 2016-02-14 07:16:16]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/20001

[commit-bot: I haz the power, 2016-02-14 07:54:31]

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

[commit-bot: I haz the power, 2016-02-14 07:54:32]

Dry run: Try jobs failed on following builders:
  linux_chromium_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[kinuko, 2016-02-14 12:51:46]

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

[commit-bot: I haz the power, 2016-02-14 12:51:56]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/40001

[kinuko, 2016-02-14 14:06:18]

Patchset #2 (id:20001) has been deleted

[kinuko, 2016-02-14 14:07:07]

Description was changed from

==========
Add utility method for more efficient WebString to base::FilePath conversion

Converting WebString to base::FilePath used to go through string16
while FilePath can directly take UTF8 data depending on platforms,
so this could be suboptimal.

Also (as we did for WebStringToGURL conversion) we can use StringPiece
to avoid extra string copy.

BUG=n/a
==========

to

==========
Add utility method for more efficient WebString to base::FilePath conversion

Converting WebString to base::FilePath used to go through string16, but
- FilePath can take UTF8 depending on platforms (e.g. on posix), and
- We can use StringPiece to avoid extra string copy when possible

BUG=n/a
==========

[commit-bot: I haz the power, 2016-02-14 14:36:24]

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

[commit-bot: I haz the power, 2016-02-14 14:36:25]

Dry run: This issue passed the CQ dry run.

[kinuko, 2016-02-15 15:40:55]

Description was changed from

==========
Add utility method for more efficient WebString to base::FilePath conversion

Converting WebString to base::FilePath used to go through string16, but
- FilePath can take UTF8 depending on platforms (e.g. on posix), and
- We can use StringPiece to avoid extra string copy when possible

BUG=n/a
==========

to

==========
Add utility method for WebString to base::FilePath conversion

Converting WebString to base::FilePath used to go through string16, but
- FilePath can take UTF8 depending on platforms (e.g. on posix), and
- We can use StringPiece to avoid extra string copy when possible

BUG=n/a
==========

[kinuko, 2016-02-15 15:40:55]

kinuko@chromium.org changed reviewers:
+ esprehn@chromium.org, thakis@chromium.org

[kinuko, 2016-02-15 15:43:38]

esprehn: blink changes
thakis: base/ changes

Could you review?  Something similar to URLConversion brettw did but for
base::FilePath.

[Nico, 2016-02-15 16:45:14]

base/ lgtm. Below I'm convincing myself that this is always better than the old
code, ok to ignore (except the test comment maybe).

https://codereview.chromium.org/1686263008/diff/40001/content/shell/renderer/...
File content/shell/renderer/layout_test/blink_test_runner.cc (left):

https://codereview.chromium.org/1686263008/diff/40001/content/shell/renderer/...
content/shell/renderer/layout_test/blink_test_runner.cc:330:
files.push_back(base::FilePath::FromUTF16Unsafe(absolute_filenames[i]));
Before:

On Windows: One conversion from WebString to string16
On Mac, Android, CrOS (SYSTEM_NATIVE_UTF8): one conversion to string16, then one
from utf16 to utf8
On Linux: One conversion from WebString to string16, then another from utf16 to
wstring, and then an elaborate SysWideToNativeMB


The WebString to string16 conversion goes through base::Latin1OrUTF16ToUTF16()
(what a strange function!) which effectively always does a copy

So currently 2 conversions on non-linux, more there

https://codereview.chromium.org/1686263008/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/platform/exported/FilePathConversion.cpp (right):

https://codereview.chromium.org/1686263008/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/platform/exported/FilePathConversion.cpp:20: // from
UTF8 or UTF16.
After:

Windows:
- 8bit:
  - ascii-only: calls FromUTF8Unsafe without conversions, which then calls
UTF8ToWide()
  - full latin-1: StringUTF8Adaptor converts from latin1 to utf8, and then
UTF8ToWide() (could probably go latin1->wide directly here)

- 16bit:
  - 0 conversions

Mac, Android, CrOS:
- 8bit:
  - ascii-only: 0 conversions
  - full latin-1: 1 conversion latin1 to utf8
-16bit:
  - 0 conversions to StringPiece16 followed by a conversion utf16->utf8 (i.e. 1
total)

Linux:
- 8bit:
  - ascii-only: 0 conversions to get the string piece, then one utf8->wstring,
then elaborate SysWideToNativeMB
  - full latin-1: 1 more conversion than ascii-only
-16bit:
  - 0 to StringPiece16, then 1 to wstring, then elaborate SysWideToNativeMB

https://codereview.chromium.org/1686263008/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/platform/exported/FilePathConversion.cpp:26: return
base::FilePath::FromUTF16Unsafe(
does this branch have test coverage?

[kinuko, 2016-02-17 14:17:52]

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

[commit-bot: I haz the power, 2016-02-17 14:18:35]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/60001

[commit-bot: I haz the power, 2016-02-17 14:21:29]

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

[commit-bot: I haz the power, 2016-02-17 14:21:29]

Dry run: Try jobs failed on following builders:
  ios_dbg_simulator_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_dbg_simulator...)
  ios_rel_device_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device_ni...)
  mac_chromium_compile_dbg_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)
  mac_chromium_gn_rel on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_gn_r...)

[esprehn, 2016-02-18 02:31:34]

This lgtm, but all your bots went red?

[kinuko, 2016-02-18 07:49:11]

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

[commit-bot: I haz the power, 2016-02-18 07:49:58]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/80001

[commit-bot: I haz the power, 2016-02-18 08:39:32]

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

[commit-bot: I haz the power, 2016-02-18 08:39:33]

Dry run: Try jobs failed on following builders:
  win_chromium_compile_dbg_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_comp...)

[kinuko, 2016-02-18 08:53:18]

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

[commit-bot: I haz the power, 2016-02-18 08:53:28]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/100001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/100001

[commit-bot: I haz the power, 2016-02-18 10:00:31]

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

[commit-bot: I haz the power, 2016-02-18 10:00:32]

Dry run: Try jobs failed on following builders:
  win_chromium_compile_dbg_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_comp...)

[kinuko, 2016-02-18 10:59:47]

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

[commit-bot: I haz the power, 2016-02-18 11:00:08]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/120001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/120001

[commit-bot: I haz the power, 2016-02-18 11:39:19]

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

[commit-bot: I haz the power, 2016-02-18 11:39:20]

Dry run: Try jobs failed on following builders:
  win_chromium_compile_dbg_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_comp...)

[kinuko, 2016-02-18 12:04:19]

Patchset #5 (id:100001) has been deleted

[kinuko, 2016-02-18 12:15:43]

Patchset #5 (id:120001) has been deleted

[kinuko, 2016-02-18 12:15:51]

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

[commit-bot: I haz the power, 2016-02-18 12:16:46]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/140001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/140001

[commit-bot: I haz the power, 2016-02-18 12:57:54]

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

[commit-bot: I haz the power, 2016-02-18 12:57:55]

Dry run: Try jobs failed on following builders:
  win_chromium_x64_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[kinuko, 2016-02-18 14:04:43]

Patchset #5 (id:140001) has been deleted

[kinuko, 2016-02-20 08:25:07]

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

[commit-bot: I haz the power, 2016-02-20 08:25:37]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/160001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/160001

[commit-bot: I haz the power, 2016-02-20 10:49:39]

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

[commit-bot: I haz the power, 2016-02-20 10:49:41]

Dry run: Try jobs failed on following builders:
  win_chromium_compile_dbg_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_comp...)

[kinuko, 2016-02-20 20:29:52]

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

[commit-bot: I haz the power, 2016-02-20 20:30:08]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/160001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/160001

[commit-bot: I haz the power, 2016-02-20 22:45:08]

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

[commit-bot: I haz the power, 2016-02-20 22:45:09]

Dry run: Try jobs failed on following builders:
  win_chromium_compile_dbg_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_comp...)

[kinuko, 2016-02-21 22:55:20]

Added test & partially reverted the code for latin1 on Windows / non-posix as it
doesn't need to go through utf-8.

Looks like I'm hitting crbug.com/586967

[kinuko, 2016-02-21 22:55:29]

The CQ bit was checked by kinuko@chromium.org

[kinuko, 2016-02-21 22:55:30]

The patchset sent to the CQ was uploaded after l-g-t-m from thakis@chromium.org,
esprehn@chromium.org
Link to the patchset: https://codereview.chromium.org/1686263008/#ps160001
(title: " ")

[commit-bot: I haz the power, 2016-02-21 22:55:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/160001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/160001

[commit-bot: I haz the power, 2016-02-21 22:58:40]

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

[commit-bot: I haz the power, 2016-02-21 22:58:41]

Try jobs failed on following builders:
  ios_dbg_simulator_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_dbg_simulator...)
  mac_chromium_compile_dbg_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)

[kinuko, 2016-02-22 03:43:49]

The CQ bit was checked by kinuko@chromium.org

[kinuko, 2016-02-22 03:43:49]

The patchset sent to the CQ was uploaded after l-g-t-m from
esprehn@chromium.org, thakis@chromium.org
Link to the patchset: https://codereview.chromium.org/1686263008/#ps180001
(title: "rebase!")

[commit-bot: I haz the power, 2016-02-22 03:43:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1686263008/180001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1686263008/180001

[commit-bot: I haz the power, 2016-02-22 05:23:27]

Description was changed from

==========
Add utility method for WebString to base::FilePath conversion

Converting WebString to base::FilePath used to go through string16, but
- FilePath can take UTF8 depending on platforms (e.g. on posix), and
- We can use StringPiece to avoid extra string copy when possible

BUG=n/a
==========

to

==========
Add utility method for WebString to base::FilePath conversion

Converting WebString to base::FilePath used to go through string16, but
- FilePath can take UTF8 depending on platforms (e.g. on posix), and
- We can use StringPiece to avoid extra string copy when possible

BUG=n/a
==========

[commit-bot: I haz the power, 2016-02-22 05:23:28]

Committed patchset #6 (id:180001)

[commit-bot: I haz the power, 2016-02-22 05:24:21]

Description was changed from

==========
Add utility method for WebString to base::FilePath conversion

Converting WebString to base::FilePath used to go through string16, but
- FilePath can take UTF8 depending on platforms (e.g. on posix), and
- We can use StringPiece to avoid extra string copy when possible

BUG=n/a
==========

to

==========
Add utility method for WebString to base::FilePath conversion

Converting WebString to base::FilePath used to go through string16, but
- FilePath can take UTF8 depending on platforms (e.g. on posix), and
- We can use StringPiece to avoid extra string copy when possible

BUG=n/a

Committed: https://crrev.com/b473f003f012766b87c4a14672f924ea7cffaea5
Cr-Commit-Position: refs/heads/master@{#376688}
==========

[commit-bot: I haz the power, 2016-02-22 05:24:22]

Patchset 6 (id:??) landed as
https://crrev.com/b473f003f012766b87c4a14672f924ea7cffaea5
Cr-Commit-Position: refs/heads/master@{#376688}