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This fixes four compounding inefficiencies that caused infobar layouts
to take waaaay longer than they should have (over 1 second in the direst
cases!). The worst manifestation of this problem could be seen by
opening the change-language panel on the translate infobar on a pre-L
device. This resulted in 3 300ms measures as well as 250ms spent
measuring text.

The fixes are:
 - InfoBarLayout was measuring each InfoBarControlLayout twice: once
   with UNSPECIFIED width and once with an exact width. Since
   InfoBarControlLayouts handle layout logic internally, they should
   only be measured once, with an exact width.
 - The infobar view's width was WRAP_CONTENT, which caused its parent,
   the wrapper view, to measure it twice. This is fixed by setting
   the width to MATCH_PARENT.
 - TranslateLanguagePanel.onItemSelected() is called twice when the
   translate panel is first created to set the initial values of the
   spinners. This resulted in two superfluous measure/layout/draw
   passes. As a fix, TranslateLanguagePanel.onItemSelected() only calls
   reloadSpinners() if the selected language has actually changed.
 - TranslateLanguagePanel.setUpSpinners() took 250ms to determine the
   width of the longest language. This CL makes this measuring logic
   smarter and avoids redundant work in two different ways: it only
   measures each language once (not once per spinner), and it only
   measures "Page language: " and "Translation language: " once.
   (instead of once per language per spinner = ~140 times each)

BUG=564406

Review URL: https://codereview.chromium.org/1560573002

Cr-Commit-Position: refs/heads/master@{#367464}