Adds 2 flags for input method features.
1) --enable-new-korean-ime, which is for new Korean IME based on Google Input Tools.
2) --enable-physical-keyboard-autocorrect, which is for suggestions on typing with physical keyboard.
For enable-physical-keyboard-autocorrect, the extension JS will use inputMethodPrivate.getInputMethodConfig API to read the flag value and turn on the feature accordingly.
BUG=422869
TEST=Verified on linux_chromeos.
Review URL: https://codereview.chromium.org/
676593004
Cr-Commit-Position: refs/heads/master@{#300892}