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We have several component extension as the initial default app, which
means set to default before user explicitly changes default app.
Audio player and the "Office Editing for Docs, Sheets & Slides" app
were not included in that list despite these are also components.

Bug: 810986
Test: unit_tests --gtest_filter=FileManagerFileTasksTest.*
Test: manually verified Office Editing shown as default

Change-Id: I1ee20773714ecda50fbe3d17f8cda1c0bb72fd96
Reviewed-on: https://chromium-review.googlesource.com/920124Reviewed-by: Naoki Fukino <fukino@chromium.org>
Commit-Queue: Tatsuhisa Yamaguchi <yamaguchi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537247}