Change GetEditableSelectionRange to use TextInputState.

All callers of GetEditableSelectionRange expects a selection in editable
text field. However, TextSelection provided by TextInputManager contains
a selection in non-editable text.

Bug: 908762
Test: content_unittests
Change-Id: Idf8618136a576a00ff2800446dae5b79e23c33c8
Reviewed-on: https://chromium-review.googlesource.com/c/1402307
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Yuichiro Hanada <yhanada@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621455}
2 files changed