Edit: Flash is only distributed with the i386 builds of Flash. The rest of the answer is based on that (I'm using 64bit)
On a 32bit computer, the Chrome version of flash will be at /opt/google/chrome/libflashplayergc.so. If you have this, you could try copying/symlinking this around, it should still be using NPAPI so should be compatible with Firefox.
If that file doesn't exist, you're probably like me and don't have it.
I have Chrome installed and it claims (in about:plugins, click the "details" link) that it's using /usr/lib/flashplugin-installer/libflashplayer.so plugin. This is the same one that Firefox is using.
You can also run locate libflash to have a quick look over the system for versions of Flash. /usr/lib/flashplugin-installer/libflashplayer.so is the only version I have on the computer (the others are symlinks).
You should note that later this year (assuming their plans turn out) Chrome/Chromium will switch to a PPAPI version of Flash (from the NPAPI one it shares with Firefox). So whatever instructions you do get, they'll stop working at some point this year... Unless Mozilla backtracks and decides to support PPAPI (which is also possible).
I have had a look at the google-chrome-stable, -beta and -unstable packages and none of them have a Flash plugin in them.
The problem might not be version bug as other answer suggesting, since it is still in chrome 29. A more concrete solution could be this.
First Download a standard Bangla font, such as Solaiman Lipi.
Install the font by copying it to either your user specific ~/.fonts folder or for system-wide effect in /usr/share/fonts/truetype folder.
Then close (if it is opened) and open the Google chrome.
Go to Settings, click on Advanced settings, in Website content section, click on the customize fonts button.
In the sans-serif font section, change the font to Solaiman Lipi.
This should solve the problem.
Credit: This page on blogspot
Some alternative fonts:
You could also install lohit bengali font and use it. to install use the command in a terminal:
sudo apt-get install fonts-lohit-beng-bengali
Or you might want to test some of the fonts from omicron-lab site
Best Answer
Each browser can fix the default font size.
In Firefox you will find these settings in Preferences -> Preferences -> content -> Fonts & Colors
In chrome (pulled from their website) :