Fix example about java_binary to java_binary instead of java_library

Fix example about java_binary to java_binary instead of java_library

Change the example provided in rules.gni for declaring a java executable
target to java_binary instead of java_library.

BUG=476112
Committed: https://crrev.com/8c8162e4c9d3cc2310cc290b10b8d509f876b607
Cr-Commit-Position: refs/heads/master@{#324932}

[jkarp, 2015-04-10 22:03:17]

jkarp@amazon.com changed reviewers:
+ cjhopman@chromium.org

[jkarp, 2015-04-10 22:03:17]

Hello, PTAL! Thanks.

[cjhopman, 2015-04-13 21:14:19]

lgtm

[jkarp, 2015-04-13 21:28:23]

The CQ bit was checked by jkarp@amazon.com

[commit-bot: I haz the power, 2015-04-13 21:29:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1075863003/1

[commit-bot: I haz the power, 2015-04-13 23:01:13]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-13 23:02:17]

Patchset 1 (id:??) landed as
https://crrev.com/8c8162e4c9d3cc2310cc290b10b8d509f876b607
Cr-Commit-Position: refs/heads/master@{#324932}