GN: Explicitly list out public headers in the blink_headers source_set

GN: Explicitly list out public headers in the blink_headers source_set

This enables "gn check" to enforce that source files that #include
these headers also declare a dependency on them in GN.

This also fixes "gn check" on Android from having errors like:

ERROR at //components/autofill/content/renderer/autofill_agent.cc:45:11: Include not allowed.
          ^--------------------------------------------
It is not in any dependency of
  //components/autofill/content/renderer:renderer
The include file is in the target(s):
  //third_party/WebKit/public:blink_headers_java_enums_srcjar__generate_enum
which should somehow be reachable.

BUG=367595
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=198439

[agrieve, 2015-07-04 02:21:45]

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

[Dirk Pranke, 2015-07-06 23:01:43]

lgtm.

+esprehn, fyi (this is the change I was talking about).

At some point we may want to add in the other private headers to the appropriate
targets as well so that 'gn check' can do proper dependency enforcement.

[esprehn, 2015-07-06 23:12:44]

esprehn@chromium.org changed reviewers:
+ esprehn@chromium.org

[esprehn, 2015-07-06 23:12:45]

lgtm

[agrieve, 2015-07-07 23:34:13]

The CQ bit was checked by agrieve@chromium.org

[commit-bot: I haz the power, 2015-07-07 23:34:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1222673004/20001

[commit-bot: I haz the power, 2015-07-08 01:06:51]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=198439

[pdr., 2015-07-08 17:59:45]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/1224843009/ by pdr@chromium.org.

The reason for reverting is: This patch is causing build failures:
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_....