Issue 702671  has been merged into this issue.

Unable to reproduce the issue on Ubuntu 14.04(xfce window manager) using latest stable 57.0.2987.110, was able to scroll clicking on the top and bottom scroll button areas.
Could you please upgrade to latest stable and help us with any other settings to reproduce the issue.

Can you describe how you have the buttons mapped in your config?

The default configuration with the Marblemouse seems to be page forward/page back. You need to let us know what you mapped these to in your x11 conf

collin@ still waiting on feedback from you.

This is how I have buttons mapped...

Section "InputClass"
Identifier "Marble Mouse"
MatchProduct "Logitech USB Trackball"
MatchIsPointer "on"
MatchDevicePath "/dev/input/event*"
Driver "evdev"
Option "Buttons" "9"
Option "ButtonMapping" "3 4 1 5 6 7 4 4 5"
Option "EmulateWheel" "true"
Option "EmulateWheelButton" "8"
Option "ZAxisMapping" "5 6"
Option "XAxisMapping" "7 4"
Option "Emulate3Buttons" "true"
EndSection

Interesting note - problem does NOT occur in a different distro, Manjaro 17, with same version of Chromium, exact same mouse, and exact same 50-marblemouse.conf file in /usr/share/X11/xorg.conf.d so am wondering if its something altogether different?  Kernel in Manjaro is 4.9.20, and in Stretch its 4.9.0 so a bit more recent in Manjaro...

Thank you for providing more feedback. Adding requester "durga.behera@chromium.org" to the cc list and removing "Needs-Feedback" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

BTW - the marblemouse is setup for left hand, and the Manjaro 17 install I tested in today is new, just did the install tonight, so was shocked when I tried the scroll buttons in Chromium in the new Manjaro install with same mouse and conf and it worked.  I really do not do a lot of hacking or tweaking with my workstations.  Prefer Debian above all others for the workstations where I earn a living, since it just works and doesn't break, but I do play with other distros on spare workstations.  Will happily suffer scroll buttons not working in Chromium - rather have a stable system than scroll buttons that work in Chromium, lol.  Firefox is fine, though - so back to it maybe its Chromium in combo with Debian?

I've confirmed that it works on Ubuntu 14.04 with the config you provided albeit I needed to roll the trackball horizontally to scroll up and down.

Are you able to compare the differences from xev on your two different platforms?

I find that the config you have posted is generating buttons 4 & 5 which is causing the scrolling correctly.

Have not used xev in recent memory need to read up on it, but Debian 9 and Manjaro 17, am using the same mouse, literally just unplugged from Debian 9 workstation (its a wired USB mouse, not wireless) and plugged into Manjaro workstation (btw - both workstations are physical devices, not vm's), and am literally using the exact same 50-marblemouse.conf file, just copied over to Manjaro.  Am not an uber-geek (wish I was) but can competently run commands when directed to do so, so if you need me to run anything, please indicate what you need me to do. I have a Jessie workstation where Chromium has never been loaded, I loaded it there and auditioned Chromium behavior.  Same version of Chromium as Debian 9 and the scroll buttons work without issue, the kernel for Jessie workstation is 3.16.0-4-amd64.  That workstation also has same mouse make/model uses same 50-marblemouse.conf file as well.  The Jessie workstation is almost the exact same hardware as the Debian 9 workstation, both Dell Optiplex 9010 only difference is that the Debian 9 workstation is the energy saving model.  Am thinking perhaps on Debian 9 I should just purge Chromium and re-install and try clean.  Can't hurt, just something I am not used to having doing with Debian, don't think I've ever had to do anything like that since I've been using Debian for over a decade now... first time for everything, lol.  Will try that and report back.  

Thank you for providing more feedback. Adding requester "brajkumar@chromium.org" to the cc list and removing "Needs-Feedback" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Have purged Chromium from Debian 9, removed chromium folder from my home directory in .config, rebooted, re-installed Chromium, rebooted and launched nice clean Chromium and alas, same issue with mouse.  Cannot use buttons for scrolling up/down.  Kind of feel silly for pointing out this issue, since I'm probably a minority, using a marblemouse and using it left handed at that... and I use two mice at once, actually, right hand I use another trackball, but that one has a scroll wheel and doesn't have any buttons custom mapped, either.  I use it to scroll in Chromium works just fine... when I remember to use it in Chromium, that is, lol...  Thanks for exploring this marblemouse issue in Chromium none the less, everyone on the Debian team does a most excellent job and you are all not nearly enough appreciated.   

This is interesting - I installed Opera web browser today to play around with it (which is based on Chromium) and I have the SAME PROBLEM with it in Debian 9 as I do with Chromium.  Cannot use buttons for scrolling.  Will install on my Jessie workstation and see if I have the same issue with Opera there or no.  Seems to be an issue with Debian 9 and Chromium based browsers...

Installed Opera on my Jessie workstation, scroll buttons function as expected.  So it seems that my Debian 9 workstation just hates Chromium based browsers.  Or at least, in conjunction with my marblemouse and its custom mapped buttons.  Both Chromium and Opera browsers work fine using scroll buttons on Jessie.

Have you tried using a different window manager on debian 9?

I think providing us with the xev results of pressing and scrolling the mouse wheel would be very useful. Just run it and copy the results from the console into a text file you can attach to this bug. I can try to see if I can try a debian 9 image in a VM with the marble mouse here.

No - have not tried a different window manager.  Am using whatever window manager ships with XFCE.  My Jessie workstation is also XFCE.  Reluctant to change window managers, since this is my primary workstation and really prefer not to break it.  Am rather attached to it, am really liking Debian 9, even if I've run across a few quirks here and there, but I know its still in testing so not critical at all about these few oddities.  Anyway, see attached file of xev, is this what you are looking for?  I did right click, left click, double right click, double left click with LARGE buttons, and single click small right and single click small left with SMALL buttons, which are mapped for incremental scrolling up/down (multiple single clicks in succession to scroll up and down).  Since I am using this mouse left handed, RIGHT big button is for normal left-click, and LEFT big button is for normal right-click, RIGHT small button is for scrolling DOWN (using thumb) and LEFT small button is for scrolling UP (using third finger - doubt you need THAT much detail, though, lol).  You brought to mind using a VM - which made a light bulb go off.  I have two windows VM's on this workstation, and I cannot use the mouse scroll buttons in these VM's, either.  With my previous install, SolydX 8 based on Jessie, I did not have this problem with these same VM's, and I don't have this problem on my Jessie workstation, either.  I don't often access these VM's so forgot to mention that mouse scroll buttons do not work in these - am using Virtualbox 5.1.18 with guest additions as same level.  My Jessie workstation is using the same version of Virtualbox.

Deleted: xev 27.8 KB

xev 27.8 KB View Download

I'm seeing these extra X11 messages compared to my testing here:

EnterNotify event, serial 37, synthetic NO, window 0x4c00001,
    root 0xe2, subw 0x0, time 26835490, (38,26), root:(909,505),
    mode NotifyGrab, detail NotifyInferior, same_screen YES,
    focus YES, state 2064

KeymapNotify event, serial 37, synthetic NO, window 0x0,
    keys:  4294967266 0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   
           0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   

I do see that the mouse is generating button 4 and button 5 which cause the scrolling. Does a mouse with wheel work correctly?

Also when you hold down the left small button and move the wheel horizontally does that work?

My Logitech M570 for right hand with scroll wheel works in Chromium.  With the marblemouse, I cannot make the mouse horizontal scroll as you have described, not to mention it is extremely awkward maneuver, lol.  However, if I grab the scrolls bars on a webpage with right big button (using thumb) and continue to hold the button,  then I can then use the marble to scroll up/down or side to side, depending which scroll bar I click and hold.  Don't often use this method as it is fatiguing on my thumb, so I tend to use keyboard page up/page down buttons for advancing and retreating vast distances, but then use small buttons to incrementally scroll up/down... which will advance or retreat by about three lines at a time.  Have been trying to think of what could be the difference between Jessie workstation and Stretch where the mouse behaves correctly in Jessie and not Stretch.  Have been using this marblemouse configuration for about 8 years now, maybe more... and its the first time I've run into a problem so begged further investigation... inquiring minds and all.  I'm flexible - I've gone to using Firefox for just about everything, even though FF is not ideal for all things.  Chromium I heavily use, though, for access to resources on my own network, servers, routers, etc.  Prefer to keep access to these resources separate.  I was using Google Chrome for certain internet tasks, but since it has the same issue as Chromium, I've changed over to FF for those tasks.  Normal web browsing, though, I use a Palemoon with a restrictive configuration.  Basically use for reading.

Are you using xf86-input-evdev or xf86-input-libinput?

I have it configured as below in a file named 50-marblemouse.conf which is in /usr/share/X11/xorg.conf.d/  It looks like evdev?

Section "InputClass"
Identifier "Marble Mouse"
MatchProduct "Logitech USB Trackball"
MatchIsPointer "on"
MatchDevicePath "/dev/input/event*"
Driver "evdev"
Option "Buttons" "9"
Option "ButtonMapping" "3 4 1 5 6 7 4 4 5"
Option "EmulateWheel" "true"
Option "EmulateWheelButton" "8"
Option "ZAxisMapping" "5 6"
Option "XAxisMapping" "7 4"
Option "Emulate3Buttons" "true"
EndSection

BTW - I took another workstation, lobotomized it, and did a clean Debian 9 install.  Same problem with scroll buttons on marble mouse with Chromium.  Before doing that, however, I did a clean Manjaro install, same version of chromium, on that same workstation, using same config file, and Chromium was fine... scroll buttons behaved as expected.  Then I lobotomized it again (as in wiped hard drive and did new partition table) and loaded Debian 9, and no joy with Chromium and mouse scroll buttons...

For the interested, I setup a virtual machine on my workstation using Virtualbox 5.1.18, the distro I used for the vm is based on Debian testing (Stretch), AV Linux 2017.3... and to my surprise (or maybe not) the scroll buttons for my marble mouse do not work at all period in the virtual machine, they will not scroll any windows at all no matter the app.  Interesting. Sorry to beat a dead horse here.  If the bug is of no interest to anyone else, you can just close this bug and put your energies in to more important things.  Its a pretty obscure issue, really... and I think the problem is with Debian Stretch.

thomas.. that is actually  issue 704410  and it is something unrelated to colin's issue.

collin@ I installed debian 9 RC3 inside a vmware instance and the scroll buttons work for me with. It could be something going on with vmware that is making it work but unfortunately since I can't repro it there isn't much I can do to try to fix it. 

I am using Virtualbox 5.1.18 - but, the problem is not restricted to vbox (and I don't really care about vbox, so no worries there).  It's bare metal as well (which I do care about).  And I am getting the same experience with different workstations (have tried three different bare metal D9 installs on three different workstations which all have different hardware) and I get the same results.  The only thing in common between them is I use XFCE (which was also the DE of the AV Linux distro I just tried in vbox, and AV Linux is also based on D9), and I do not boot to login screen, I boot to tty, login and then issue startx command.

And just for clarification, it is only my Logitech Trackman Marble Mouse with small buttons mapped for incremental scrolling up/down where I have the issue.  My other mouse I use with right hand, the Logitech M570 with a scroll wheel - this works fine everywhere regardless.  If I hadn't been using the same configuration file for my marblemouse in Linux for almost 10 years, with no incident regardless the distro, I would not have thought anything of the oddness.  If I had just now tried the marblemouse for first time ever and scroll buttons didn't work, then I would have just chalked it up to something that doesn't work right in linux.  It happens.  Its just curious that something that has worked flawlessly for me for that long, across distros, AND inserting the same 50-marblemouse.conf file into every distro and always having mapped scroll buttons function?  You can see how I would be curious as to what has changed and where.  Somehow do not believe it is Chromium, directly, but rather the way it is playing with D9 and X11 and how my marblemouse is playing with them.  Something somewhere changed.  Maybe its X I don't know.  Can't blame XFCE 4.12, since Manjaro uses that version of XFCE and I don't have any issues there at all with my marblemouse, not even with Chromium.  On D9, I have no scroll issues at all with Marble mouse, ONLY with Chromium do I have this issue.  Its puzzling and I love puzzles, and can usually search around for info to fix things, or work it out on my own, but when it gets down to the nitty gritty stuff, I am unable to fix myself.  Right now in D9, have switched to Firefox and Palemoon for everything, and still use Chromium to access my in-house resources, I just suffer not being able to use scroll buttons with marblemouse.  Since I am dependent on Debian (being rock solid as it is and dependable), won't use any other distro else for my primary workstations.  And I like the new features in Stretch, so not inclined to go back to Jessie, where everything works just fine in Jessie.  It is what it is - just wish I knew WHAT it is, so I could at least discover where the problem lies, even if its something that cannot be rectified.  For the curious, attached pic is of the infamous marblemouse...

Deleted: 20170420_074724.jpg 80.5 KB

	20170420_074724.jpg 80.5 KB View Download