tree 4e29fe8f60c834d74f83a5bfb0b90b5b2c391f6e
parent 406ae08b92f78f26fe83830897570c9db1ab23aa
parent ea7a5dbc54ccaaf858e63177f1c1b66bdc361d54
author Jin Cao <jinyan@google.com> 1410553866 +0000
committer James Lemieux <jplemieux@google.com> 1410811271 -0700

Choose thread icon more carefully

b/17298161

Choosing the avatar to draw as the thread icon follows this algorithm:

1) Prefer the sender of the first unread message.
2) If all messages are read, prefer the last sender that is not the
   current account.
3) If all messages were sent from the current account (e.g. user is
   emailing themselves), use the last sender (aka current account).

In the process of doing this work the last remaining dependency on
DividedImageCanvas was broken, so it could be removed at this time.

Tests confirming the new behavior have been added to SendersFormattingTests.

Change-Id: If8e066de8cb98f2f95b019a88a2fdadc2f9f5090