Chrome Version: 55.0.2883.105
Chrome OS Version: 8872.76.0 (Official Build) stable-channel veyron_minnie
Chrome OS Platform: Asus C100P
Network info: WiFi, WPA2 Personal, Apple AirPort, 5GHz

UI>Input>Text>IME

Steps To Reproduce:
1. Download the attached imi-docs-bugs.zip file
2. Double-click the downloaded .zip to mount it as a disk
3. Copy the mounted item to a folder (so that you've got the unzipped folder somewhere accessible)
4. Open URL: chrome://extensions (check Developer mode if it's unchecked)
5. Press "Load unpacked extension…"
6. Navigate to the unzipped folder from step 3 above
7. Press Open
*. You should see "IME / Google Docs Bug Demo" listed in your extensions
8. Open URL: chrome://settings
9. Under Device, press "Keyboard settings"
10. Under Keyboard settings, click "Change language and input settings"
11. Under Languages, click "English (United States)"
12. Scroll to the bottom of the right-hand list under Input Methods and click "IMEDocsBugs" to activate the input method
13. Press "Done"
14. Open a new Google Docs (word processing) document
15. Click on "US" at the bottom right
16. Click on "US Keyboard"
17. Click on "IMEDocsBugs" to change the input method to the one which shows the bug
18. Hold the shift key and type: "X" (i.e. type capital letter X)

Expected Result:
"X" is replaced by "zzz" (i.e. three lowercase z's)

Actual Result:
Nothing happens (X does not appear, nor does zzz)

How frequently does this problem reproduce? (Always, sometimes, hard to
reproduce?)
Always

What is the impact to the user, and is there a workaround? If so, what is
it?
The IME does not function in Google Docs but works elsewhere.

Please provide any additional information below. Attach a screen shot or
log if possible.

"X" expands to "zzz" when typed in:
- the omnibar
- on jsfiddle.net
- Microsoft Word online
- Pages online (iCloud)

"Z" does not expand to "TextExpander" when typed in:
- Google Docs

The calls in the source which fail on Google Docs is this set of three:
chrome.input.ime.commitText({"contextID":contextID, "text":'z'});
chrome.input.ime.commitText({"contextID":contextID, "text":'z'});
chrome.input.ime.commitText({"contextID":contextID, "text":'z'});

This discrepancy makes it difficult to develop an input method which functions in Google Docs, etc.