GitLab

This CL moves more implementation files of public/web/ classes to
core/exported/. Files moved:

- WebDOMMessageEvent.cpp.
- WebContextFeatures.cpp.
- WebLanguageDetectionDetails.cpp
- WebPluginDocument.cpp.
- WebSearchableFormData.cpp
- WebScopedWindowFocusAllowedIndicator.cpp.

Bug: 712963
Change-Id: Ib9c92047516cd5401fd6f6406c1b9967f6d49b86
Reviewed-on: https://chromium-review.googlesource.com/530427Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Stuart Langley <slangley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#478519}