gn: add support for clang for MIPS

gn: add support for clang for MIPS

This changes enables chrome for MIPS (Linux and Android)
to be compiled with clang when using gn build.

However, there are still few issues for build to complete successfully:

- "treat_warnings_as_errors=false" must be set for both Android and Linux.
- in case of Linux ldflags retreived by 'exec_script("sysroot_ld_path.py",..'
  are ignored by linker, which is causing link failure for 'chrome' target.

BUG=gn gen for MIPS
TEST=gn gen out-gn/mips --args="is_debug=false target_os=\"android\" target_cpu=\"mipsel\" is_clang=true treat_warnings_as_errors=false"
     ninja -C out-gn/mips chrome_public_apk

Committed: https://crrev.com/af7fa747c3c2e433028103b45173c0275333abc7
Cr-Commit-Position: refs/heads/master@{#362002}

[gordanac, 2015-11-25 16:04:47]

Description was changed from

==========
gn: add support for clang for MIPS

This changes enables chrome for MIPS (Linux and Android)
to be compiled with clang when using gn build.

BUG=gn gen for MIPS
TEST=gn gen out-gn/mips --args="is_debug=false target_os=\"linux\"
target_cpu=\"mipsel\" is_clang=true"
     ninja -C out-gn/mips chrome
==========

to

==========
gn: add support for clang for MIPS

This changes enables chrome for MIPS (Linux and Android)
to be compiled with clang when using gn build.

BUG=gn gen for MIPS
TEST=gn gen out-gn/mips --args="is_debug=false target_os=\"linux\"
target_cpu=\"mipsel\" is_clang=true"
     ninja -C out-gn/mips chrome
==========

[gordanac, 2015-11-25 16:04:47]

gordana.cmiljanovic@imgtec.com changed reviewers:
+ dpranke@chromium.org

[gordanac, 2015-11-25 16:05:29]

Please take a look.

[Dirk Pranke, 2015-11-25 19:13:54]

lgtm.

sbc, agrieve: FYI.

[gordanac, 2015-11-26 18:45:27]

I just realized the description of the change is misleading:
gn gen is going to work with this change but there are still build issues.

The additional issues are:
1. There is a warning in Webkit, but due to '-Werror' it is treated as error; 
   Can be temporary resolved with "treat_warnings_as_errors=false"
2. Linker paths returned by 'exec_script("sysroot_ld_path.py", ..' are ignored
by ld.bfd
   since linker line conatins '\' char before every space
   in the value returned by the script. This is causing linker failues
   as some of the libraries cannot be located

With workaround for 1. Android GN build is OK.
I still don't have a solution for 2.

I have updated the description accordingly.

[gordanac, 2015-11-26 18:47:34]

Description was changed from

==========
gn: add support for clang for MIPS

This changes enables chrome for MIPS (Linux and Android)
to be compiled with clang when using gn build.

BUG=gn gen for MIPS
TEST=gn gen out-gn/mips --args="is_debug=false target_os=\"linux\"
target_cpu=\"mipsel\" is_clang=true"
     ninja -C out-gn/mips chrome
==========

to

==========
gn: add support for clang for MIPS

This changes enables chrome for MIPS (Linux and Android)
to be compiled with clang when using gn build.

However, there are still few issues for build to complete successfully:

- "treat_warnings_as_errors=false" must be set for both Android and Linux. 
- in case of Linux ldflags retreived by 'exec_script("sysroot_ld_path.py",..'
  are ignored by linker, which is causing link failure for 'chrome' target.

BUG=gn gen for MIPS
TEST=gn gen out-gn/mips --args="is_debug=false target_os=\"android\"
target_cpu=\"mipsel\" is_clang=true treat_warnings_as_errors=false"
     ninja -C out-gn/mips chrome_public_apk
==========

[gordanac, 2015-11-27 14:24:14]

The CQ bit was checked by gordana.cmiljanovic@imgtec.com

[commit-bot: I haz the power, 2015-11-27 14:24:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1475943003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1475943003/1

[commit-bot: I haz the power, 2015-11-27 15:05:39]

Description was changed from

==========
gn: add support for clang for MIPS

This changes enables chrome for MIPS (Linux and Android)
to be compiled with clang when using gn build.

However, there are still few issues for build to complete successfully:

- "treat_warnings_as_errors=false" must be set for both Android and Linux. 
- in case of Linux ldflags retreived by 'exec_script("sysroot_ld_path.py",..'
  are ignored by linker, which is causing link failure for 'chrome' target.

BUG=gn gen for MIPS
TEST=gn gen out-gn/mips --args="is_debug=false target_os=\"android\"
target_cpu=\"mipsel\" is_clang=true treat_warnings_as_errors=false"
     ninja -C out-gn/mips chrome_public_apk
==========

to

==========
gn: add support for clang for MIPS

This changes enables chrome for MIPS (Linux and Android)
to be compiled with clang when using gn build.

However, there are still few issues for build to complete successfully:

- "treat_warnings_as_errors=false" must be set for both Android and Linux. 
- in case of Linux ldflags retreived by 'exec_script("sysroot_ld_path.py",..'
  are ignored by linker, which is causing link failure for 'chrome' target.

BUG=gn gen for MIPS
TEST=gn gen out-gn/mips --args="is_debug=false target_os=\"android\"
target_cpu=\"mipsel\" is_clang=true treat_warnings_as_errors=false"
     ninja -C out-gn/mips chrome_public_apk
==========

[commit-bot: I haz the power, 2015-11-27 15:05:42]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-27 15:06:27]

Description was changed from

==========
gn: add support for clang for MIPS

This changes enables chrome for MIPS (Linux and Android)
to be compiled with clang when using gn build.

However, there are still few issues for build to complete successfully:

- "treat_warnings_as_errors=false" must be set for both Android and Linux. 
- in case of Linux ldflags retreived by 'exec_script("sysroot_ld_path.py",..'
  are ignored by linker, which is causing link failure for 'chrome' target.

BUG=gn gen for MIPS
TEST=gn gen out-gn/mips --args="is_debug=false target_os=\"android\"
target_cpu=\"mipsel\" is_clang=true treat_warnings_as_errors=false"
     ninja -C out-gn/mips chrome_public_apk
==========

to

==========
gn: add support for clang for MIPS

This changes enables chrome for MIPS (Linux and Android)
to be compiled with clang when using gn build.

However, there are still few issues for build to complete successfully:

- "treat_warnings_as_errors=false" must be set for both Android and Linux.
- in case of Linux ldflags retreived by 'exec_script("sysroot_ld_path.py",..'
  are ignored by linker, which is causing link failure for 'chrome' target.

BUG=gn gen for MIPS
TEST=gn gen out-gn/mips --args="is_debug=false target_os=\"android\"
target_cpu=\"mipsel\" is_clang=true treat_warnings_as_errors=false"
     ninja -C out-gn/mips chrome_public_apk

Committed: https://crrev.com/af7fa747c3c2e433028103b45173c0275333abc7
Cr-Commit-Position: refs/heads/master@{#362002}
==========

[commit-bot: I haz the power, 2015-11-27 15:06:28]

Patchset 1 (id:??) landed as
https://crrev.com/af7fa747c3c2e433028103b45173c0275333abc7
Cr-Commit-Position: refs/heads/master@{#362002}