This is a timing-changing patch. Here are the details: * The page text capture machinery no longer uses archaic timers to determine the best time to grab the text from the the document. Instead, it relies on the MeaningfulLayout signals that are coming from Blink. * These signals are keyed off the compositor putting up frames, which has an interesting side effect -- at least on some platforms (CrOS and Linux), this signal will not be issued until document/frame/tab is active, which is perfectly fine for our purposes. * As a side comment, we should probably unify our position on whether compositor puts up frames for inactive tabs. * As another side comment, this would help simplify the logic in translate bubbles that watches for tab to become active. * In many cases, the timing is much shorter than before, especially for smaller pages. This is good (faster!), but also means that some tests had to be tweaked to start listening for language detection notifications a bit earlier. * Fundamentally, this is a change in timing, not behavior, so the existing test coverage seemed sufficient. * The new plumbing is still incompatible with out-of-process iframes (OOPIF) and will need to be fixed up accordingly. BUG=521166 R=jam,andrewhayden,jochen Review URL: https://codereview.chromium.org/1398823004 Cr-Commit-Position: refs/heads/master@{#372891}