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This is prep for tooltip improvement: https://codereview.chromium.org/924433002/ (WIP)

* Consolidated GetMaxWidth
* Eliminate screen type argument. This can be obtained from tooltip window.
* Move tooltip truncate code from TooltipManager to TooltipController

BUG=None
TEST=no functional change. all test should pass.

Review URL: https://codereview.chromium.org/916423002

Cr-Commit-Position: refs/heads/master@{#317081}