WebView: Cleanup class/struct forward declarations

WebView: Cleanup class/struct forward declarations

Remove useless class and struct forward declarations, and add
missing ones in android_webview header files.

BUG=662195
Committed: https://crrev.com/51f0dc6ccc9836e4afa5fde2fa76113afeef29f3
Cr-Commit-Position: refs/heads/master@{#435590}

[jbriance, 2016-11-30 14:02:10]

jbriance@cisco.com changed reviewers:
+ torne@chromium.org

[Torne, 2016-12-01 10:25:13]

lgtm

[jbriance, 2016-12-01 10:26:55]

The CQ bit was checked by jbriance@cisco.com

[commit-bot: I haz the power, 2016-12-01 10:27:08]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-12-01 10:49:14]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1480588015425400, "parent_rev":
"940824d77542c7a4f447c7c7351c27af2a76cc48", "commit_rev":
"288e8e37965cdd1ed0cf99d455ac1ff58151718b"}

[commit-bot: I haz the power, 2016-12-01 10:49:41]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-12-01 10:51:32]

Description was changed from

==========
WebView: Cleanup class/struct forward declarations

Remove useless class and struct forward declarations, and add
missing ones in android_webview header files.

BUG=662195
==========

to

==========
WebView: Cleanup class/struct forward declarations

Remove useless class and struct forward declarations, and add
missing ones in android_webview header files.

BUG=662195

Committed: https://crrev.com/51f0dc6ccc9836e4afa5fde2fa76113afeef29f3
Cr-Commit-Position: refs/heads/master@{#435590}
==========

[commit-bot: I haz the power, 2016-12-01 10:51:33]

Patchset 1 (id:??) landed as
https://crrev.com/51f0dc6ccc9836e4afa5fde2fa76113afeef29f3
Cr-Commit-Position: refs/heads/master@{#435590}