Add precompiled headers to GN build for large targets.

Add precompiled headers to GN build for large targets.

Turns on precompiled header support in the GN build on Windows, and adds the precompiled header config to most large-ish targets in the build.

Removes Windows files from the precompiled header. This does not seem to affect the build speed much because most Chrome files don't depend on Windows any more. And windows.h injects typedefs and defines that conflict with some third party libraries and prevent using precompiled headers for those targets or any target that includes them.

I counted ~50 files or bigger as large. The 50 file threshold is based on some previous approximate measurements (since the precompile step is an extra per-target compile, it can actually make small targets compile slower).

For borderline cases, I added the precompiled header flag if I thought it was likely to have more files added, and didn't add it if I thought the target was likely to be static.

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Committed: https://crrev.com/8f3218985dde74063ccc362da47803be163f3165
Cr-Commit-Position: refs/heads/master@{#340535}

[brettw, 2015-07-23 18:18:35]

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

[commit-bot: I haz the power, 2015-07-23 18:19:24]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1250273002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1250273002/1

[commit-bot: I haz the power, 2015-07-23 18:22:34]

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

[commit-bot: I haz the power, 2015-07-23 18:22:35]

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_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)
  win_chromium_compile_dbg_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_comp...)

[brettw, 2015-07-23 19:28:48]

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

[commit-bot: I haz the power, 2015-07-23 19:29:22]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1250273002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1250273002/20001

[brettw, 2015-07-23 19:33:51]

brettw@chromium.org changed reviewers:
+ dpranke@chromium.org

[Dirk Pranke, 2015-07-23 20:20:17]

lgtm

[commit-bot: I haz the power, 2015-07-23 23:21:11]

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

[commit-bot: I haz the power, 2015-07-23 23:21:12]

Dry run: Try jobs failed on following builders:
  win8_chromium_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win8_chromium_ng/...)

[brettw, 2015-07-24 21:21:25]

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

[commit-bot: I haz the power, 2015-07-24 21:21:57]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1250273002/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1250273002/60001

[commit-bot: I haz the power, 2015-07-24 23:02:00]

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

[commit-bot: I haz the power, 2015-07-24 23:02:01]

Dry run: This issue passed the CQ dry run.

[brettw, 2015-07-27 18:00:17]

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

[commit-bot: I haz the power, 2015-07-27 18:03:01]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1250273002/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1250273002/80001

[brettw, 2015-07-27 19:23:38]

The CQ bit was unchecked by brettw@chromium.org

[brettw, 2015-07-27 19:23:44]

The CQ bit was checked by brettw@chromium.org

[brettw, 2015-07-27 19:23:44]

The patchset sent to the CQ was uploaded after l-g-t-m from dpranke@chromium.org
Link to the patchset: https://codereview.chromium.org/1250273002/#ps80001
(title: "mergey-wergey")

[commit-bot: I haz the power, 2015-07-27 19:25:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1250273002/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1250273002/80001

[commit-bot: I haz the power, 2015-07-27 19:45:38]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2015-07-27 19:47:06]

Patchset 5 (id:??) landed as
https://crrev.com/8f3218985dde74063ccc362da47803be163f3165
Cr-Commit-Position: refs/heads/master@{#340535}

[Dirk Pranke, 2015-07-28 00:48:04]

A revert of this CL (patchset #5 id:80001) has been created in
https://codereview.chromium.org/1260793006/ by dpranke@chromium.org.

The reason for reverting is: Speculatively reverting this, in thinking that
maybe this broke incremental builds on the Win GN bots, e.g.:

http://build.chromium.org/p/chromium.win/builders/Win%20x64%20GN/builds/4709.