Add abstractions that let embedders drive tests of WebContents.

Add abstractions that let embedders drive tests of WebContents, without exposing the internals of content/.

A separate WebContentsTester interface is used.  For reasons this approach was chosen, see comments on the interface.

As part of this work, removed a bunch of references to TabContents from Chrome, some of which were true usages (leaked to Chrome via the test_tab_contents.h header), others of which were just forward declarations and never used.  Also removed a chunk of code from autofill_manager.cc that isn't called from anywhere that referenced TabContents.

TBR=ben@chromium.org
BUG=98716
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=128198

[Jói, 2012-03-14 15:52:15]

Ended up with the same approach as for TestRenderViewHost, for similar reasons,
see comments on WebContentTester.

Cheers,
Jói

[jam, 2012-03-14 16:58:21]

lgtm

[commit-bot: I haz the power, 2012-03-15 13:19:02]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/joi@chromium.org/9706012/4003

[commit-bot: I haz the power, 2012-03-15 13:19:25]

Can't apply patch for file
chrome/browser/ui/webui/sync_internals_ui_unittest.cc.
While running patch -p1 --forward --force;
patching file chrome/browser/ui/webui/sync_internals_ui_unittest.cc
Hunk #1 FAILED at 1.
Hunk #2 succeeded at 13 with fuzz 1 (offset -3 lines).
1 out of 2 hunks FAILED -- saving rejects to file
chrome/browser/ui/webui/sync_internals_ui_unittest.cc.rej

[commit-bot: I haz the power, 2012-03-15 13:28:14]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/joi@chromium.org/9706012/2095

[commit-bot: I haz the power, 2012-03-15 14:29:04]

Try job failure for 9706012-2095 (retry) on win for step "compile" (clobber
build).
It's a second try, previously, step "compile" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win&number...

[commit-bot: I haz the power, 2012-03-15 15:46:00]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/joi@chromium.org/9706012/4005

[commit-bot: I haz the power, 2012-03-15 16:09:25]

Try job failure for 9706012-4005 (retry) on linux_chromeos for step "compile"
(clobber build).
It's a second try, previously, step "compile" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_chro...

[commit-bot: I haz the power, 2012-03-15 18:21:58]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/joi@chromium.org/9706012/103

[commit-bot: I haz the power, 2012-03-15 20:50:42]

Try job failure for 9706012-103 (retry) on win for step "compile" (clobber
build).
It's a second try, previously, step "compile" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win&number...

[commit-bot: I haz the power, 2012-03-15 21:53:49]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/joi@chromium.org/9706012/5010

[commit-bot: I haz the power, 2012-03-15 21:54:07]

Can't apply patch for file
chrome/browser/content_settings/tab_specific_content_settings_unittest.cc.
While running patch -p1 --forward --force;
patching file
chrome/browser/content_settings/tab_specific_content_settings_unittest.cc
Hunk #1 FAILED at 1.
1 out of 1 hunk FAILED -- saving rejects to file
chrome/browser/content_settings/tab_specific_content_settings_unittest.cc.rej

[commit-bot: I haz the power, 2012-03-21 13:20:36]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/joi@chromium.org/9706012/15034

[commit-bot: I haz the power, 2012-03-21 14:18:35]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/joi@chromium.org/9706012/17005

[commit-bot: I haz the power, 2012-03-21 16:49:23]

Try job failure for 9706012-17005 (retry) on win_rel for step "ui_tests"
(clobber build).
It's a second try, previously, step "compile" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...