How did my Google Chrome get switched to the "dev-m" channel?

Question

I have a typical installation of Google Chrome on my personal Windows 7 PC. I have never had trouble with automatic updates.
This evening I noticed some new behavior, so I went to the "About" page and saw some unusual information. The latest version is listed as 38.0.2125.111 dev-m and there was additionally a message that said "Updates have been disabled by administrator". (I have full administrator access and I have never disabled updates).

Based on some searching, I fixed the "disabled updates" issue by changing the value of "UpdateDefault" from 0 to 1 in the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Update. My About Page currently says "Google Chrome is up-to-date" again.

However, I'm curious about the "dev-m" part of the version number. I have never installed Chrome Canary or anything like that. Is "dev-m" supposed to be part of the version number in the stable normal release? If not, how did I get onto the dev-m update path and how do I get off of it?

Fuller explanation of symptoms:
I returned to my desk to find that Chrome was open with all of my typical tabs open, as well as the settings page for an Extension (which I foolishly closed before remembering which one it was). I did not think much of this, assuming that I had forgotten to close the browser earlier.
I closed Chrome and re-opened it and noticed that instead of the "head icons" in the upper left to switch profiles, there was a "name dropdown" on the upper right with different behavior. I also noticed that google.com was listening for "OK, Google" from my microphone which also was a new feature. This is why I went to look at the version number in the first place.
Upon reinstalling the stable version (see comments and my own answer), these 2 features were reverted.

I also noticed just now that one of my extensions -- "Notes for Gmail" -- has been automatically disabled by Chrome saying it may be infected by malware. This could possibly be related to my installation of Chrome getting screwed up.

Nobody has had physical access to this PC/browser in the last 48 hours other than myself.

UPDATE: This happened again, without explanation, a few weeks later! I closed the browser (running "stable" that I had reinstalled after asking this question), and reopened the browser a few minutes later without leaving my desk and it was suddenly showing up as the dev-m version. I had to shut down Chrome completely, reinstall the 'stable' branch from the website, and change the registry entry to reenable automatic updates.

Any clue as to what is going on?

Solution

Not sure if this helps, but I am aware that malware can cause this to happen. I recently had my PC infected by some of these coupon viruses (inadvertently installed by my wife whilst installing other free software) this changed my home page and caused web searches to display potentially unwanted results (identified as dangerous by my antivirus software). When clicking on an appropriate link to a trusted site such as amazon, the screen would jump and suddenly display random products. My pop-up blocker became disabled and could not be re-enabled. When I tried to re-install the pop up blocker extension, it kept saying 'timed out network error'.

When checking the extension section of Google, I noticed that my safe web search software was also disabled and various coupon extensions had been added and enabled (I think the names were king coupon and coupon savers and others similar). My Google version also became the dev m version and like you I have had to adjust the settings using regedit to allow updates.

I have used the control panel to remove as many of these coupon things as I could find (but they seem to keep appearing) and also been through my computer to remove the physical folders, I had to run my anti virus scan quite a few times as some residual things could not be quarantined. It really has been a pain, I am currently still on the dev m version, but having seen this post I may remove my current version and do a completely new install of chrome.

Comments

[Ramhound]

Simplest solution. Just reinstall the stable Chrome branch. Chrome documentation here

[Josh]

I tried this. The version number didn't change.

[Josh]

I did not uninstall. But I realized that Chrome was still "running in the background". When I completely closed Chrome and re-ran, I got a popup message that said something like "your user-level chrome installation has been replaced with an administrator-level installation", and then it started up and now it has just "m" in the version number instead of "dev-m". Please post your comment as a solution so I can mark it as best.

[Josh]

OK, I have posted my own answer then. I was trying to give you some credit, even though this was something I tried independently and had simply missed a step.

[Josh]

The reason this came up, specifically, was that I noticed a sudden visual change in how profile-switching worked. When I switched back to the "m" channel, profile-switching looked like what I'd expected, and what I had been experiencing earlier in the day today. Just weird.

[Josh]

My son was playing web games on my computer a while ago, and it did cause some kind of popup malware in Firefox (which went away after uninstalling/reinstalling that browser) but he hadn't used Chrome. Still I will take a look, especially if it happens a third time.

[Josh]

I definitely found some ad-malware and uninstalled it. Marking this as best answer because it seemed helpful, but I might unmark it if the dev-m channel comes back...