Resubmit 21609003: Move ExtensionError to extensions/, add error limits

Resubmit 21609003: Move ExtensionError to extensions/, add error limits

Added in a fix for the memory leak.

Move ExtensionError class to extensions/browser/, since it doesn't need to be in chrome/.
Limit the number of errors stored per extension to 100.
Store errors in a map, keyed by Extension ID, since that is how we will likely be accessing them.

BUG=21734
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=216871

[Devlin, 2013-08-08 23:24:12]

Resubmit of 21609003, which was reverted for a memory failure.  Found the leak,
and this one passes (see Valgrind trybot results).

https://codereview.chromium.org/22647007/diff/1/chrome/browser/extensions/err...
File chrome/browser/extensions/error_console/error_console.cc (right):

https://codereview.chromium.org/22647007/diff/1/chrome/browser/extensions/err...
chrome/browser/extensions/error_console/error_console.cc:32: delete *iter;
Forgot to delete *iter here.

[Matt Perry, 2013-08-09 00:25:30]

lgtm

[Yoyo Zhou, 2013-08-09 00:26:52]

LGTM

[commit-bot: I haz the power, 2013-08-09 16:04:36]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rdevlin.cronin@chromium.org/22647007/1

[commit-bot: I haz the power, 2013-08-09 17:59:58]

Step "update" is always a major failure.
Look at the try server FAQ for more details.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[commit-bot: I haz the power, 2013-08-09 18:20:55]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rdevlin.cronin@chromium.org/22647007/2...

[commit-bot: I haz the power, 2013-08-09 18:27:40]

Step "update" is always a major failure.
Look at the try server FAQ for more details.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=android_db...

[commit-bot: I haz the power, 2013-08-09 22:00:17]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rdevlin.cronin@chromium.org/22647007/2...

[commit-bot: I haz the power, 2013-08-10 15:30:54]

Change committed as 216871