Change signature of |ui::ElideText()|. Add a truncate mode.

Change signature of |ui::ElideText()|. Add a truncate mode.

The new truncate mode is needed by my upcoming changes to
rewrite CanvasSkia::DrawText().

Part of the change is changing the binary search code to a
more traditional form that also makes the truncate mode
work correctly. This is covered by the new unit tests.

BUG=105550
TEST=New and existing tests in text_elider_unittest.cc.
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=114063

[sky, 2011-12-12 17:25:56]

LGTM

[commit-bot: I haz the power, 2011-12-12 19:23:16]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/asvitkine@chromium.org/8917011/5014

[commit-bot: I haz the power, 2011-12-12 19:23:20]

Can't process patch for file
chrome/browser/ui/cocoa/omnibox/omnibox_popup_view_mac.mm.
File's status is None, patchset upload is incomplete.