Google chrome -
Google Chrome is a web browser developed by Google Inc.
Configuration
The Google Chrome configuration can be found in the Preferences file. From the Chromium site, 'Preferences are kept in a file named "Preferences", which every Chromium / Google Chrome user will have in their own user directory.' The file combines some settings from the policies, master_preferences, and local state.
There might be a copy of the Preferences file called Secure Preferences. The purpose of the file is so that the browser can compare the saved profile to a "good copy" (the Secure Preferences file), and if the two do not match then the browser will reset the settings when it is restarted, as explained here).
On Linux
/home/$USER/.config/google-chrome/Default/Preferences /home/$USER/.config/google-chrome/Default/Secure Preferences 
On MacOS-X
/Users/$USER/Library/Application Support/Google/Chrome/Default/Preferences /Users/$USER/Library/Application Support/Google/Chrome/Default/Secure Preferences 
On Windows XP
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Google\Chrome\User Data\Default\Preferences C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Google\Chrome\User Data\Default\Secure Preferences 
On Windows Vista and later
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\Default\Preferences C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\Default\Secure Preferences 
Or for Chrome SxS (Chrome side-by-side)
C:\Users\%USERNAME%\AppData\Local\Google\Chrome SxS\User Data\Default\Preferences C:\Users\%USERNAME%\AppData\Local\Google\Chrome SxS\User Data\Default\Secure Preferences 
Or for Chromium
On Linux
/home/$USER/.config/chromium/Default/Preferences /home/$USER/.config/chromium/Default/Secure Preferences 
On MacOS-X
/Users/$USER/Library/Application Support/Chromium/Default/Preferences /Users/$USER/Library/Application Support/Chromium/Default/Secure Preferences 
On Windows XP
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Chromium\User Data\Default\Preferences C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Chromium\User Data\Default\Secure Preferences 
On Windows Vista and later
C:\Users\%USERNAME%\AppData\Local\Chromium\User Data\Default\Preferences C:\Users\%USERNAME%\AppData\Local\Chromium\User Data\Default\Secure Preferences 
In browser way to control some settings:
chrome://extensions/ chrome://flags chrome://settings 
Useful values in the Preferences file
Signed in users are stored here, along with timestamps for when they first and last used this profile.
Under "plugins" you can find whether the plugin is enabled, the name, the path, and the version. (If the plugin provides all those values.)
Installed Extensions
This file contains several useful details about the installed extensions (under "extensions"):
"install_time": The timestamp of when the extension was installed in this Chrome profile.
"manifest": full extension manifest JSON
"key": the key associated with the extension (Used to determine the Extension ID)
"path": the Extension/ sub-path that the code is stored in under the profile
"state": The current state of the extension from this Chrome Profile's perspective.
0: DISABLED
1: ENABLED
2: EXTERNAL_EXTENSION_UNINSTALLED
DNS Prefetching
DNS is prefetched for related sites, e.g. links on the page. This behavior is controlled by the setting "Predict network actions to improve page load performance", which is enabled by default.
If enabled the Preferences file contains:
"dns_prefetching": { "enabled": true, 
If disabled the Preferences file contains:
"dns_prefetching": { "enabled": false, 
Start-up DNS queries
When Chrome starts it queries for several non-existing hostnames that consists of a 10 random characters, E.g.
ttrgoiknff.mydomain.com bxjhgftsyu.mydomain.com yokjbjiagd.mydomain.com 
This is used to determine if your ISP is hijacking NXDOMAIN results.
Disk Cache
Google Chrome uses multiple caches, from 3:
// The types of caches that can be created. enum CacheType { DISK_CACHE, // Disk is used as the backing storage. MEMORY_CACHE, // Data is stored only in memory. MEDIA_CACHE, // Optimized to handle media files. APP_CACHE, // Backing store for an AppCache. SHADER_CACHE, // Backing store for the GL shader cache. PNACL_CACHE, // Backing store the PNaCl translation cache }; 
Note that \$PROFILE (or %PROFILE%) the paths below is the profile dependent subdirectory which is normally Default but also could be Profile1, Profile2, etc.
The Google Chrome disk cache uses the Chrome Disk Cache Format and can be found in:
On Linux
/home/$USER/.cache/chromium/$PROFILE/Cache/ /home/$USER/.cache/google-chrome/$PROFILE/Cache/ /home/$USER/.config/chromium/$PROFILE/Cache/ /home/$USER/.config/google-chrome/$PROFILE/Cache/ /home/$USER/.cache/chromium/$PROFILE/Media Cache/ /home/$USER/.cache/google-chrome/$PROFILE/Media Cache/ /home/$USER/.config/chromium/$PROFILE/Media Cache/ /home/$USER/.config/google-chrome/$PROFILE/Media Cache/ /home/$USER/.config/chromium/$PROFILE/Application Cache/Cache/ /home/$USER/.config/google-chrome/$PROFILE/Application Cache/Cache/ /home/$USER/.config/chromium/$PROFILE/GPUCache/ /home/$USER/.config/google-chrome/$PROFILE/GPUCache/ /home/$USER/.cache/chromium/PnaclTranslationCache/ /home/$USER/.cache/google-chrome/PnaclTranslationCache/ 
On MacOS-X
/Users/$USER/Library/Caches/Chromium/$PROFILE/Cache /Users/$USER/Library/Caches/Google/Chrome/$PROFILE/Cache 
TODO confirm the following paths
/Users/$USER/Caches/Chromium/$PROFILE/Cache/ /Users/$USER/Caches/Google/Chrome/$PROFILE/Cache/ /Users/$USER/Library/Caches/Chromium/$PROFILE/Media Cache /Users/$USER/Library/Caches/Google/Chrome/$PROFILE/Media Cache /Users/$USER/Library/Application Support/Chromium/$PROFILE/Application Cache/Cache/ /Users/$USER/Library/Application Support/Google/Chrome/$PROFILE/Application Cache/Cache/ /Users/$USER/Library/Application Support/Chromium/$PROFILE/GPUCache/ /Users/$USER/Library/Application Support/Google/Chrome/$PROFILE/GPUCache/ /Users/$USER/Library/Caches/Chromium/PnaclTranslationCache/ /Users/$USER/Library/Caches/Google/Chrome/PnaclTranslationCache/ 
On Windows XP
TODO confirm the following paths
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Chromium\User Data\Cache\ C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Google\Chrome\User Data\Cache\ 
On Windows Vista and later
C:\Users\%USERNAME%\AppData\Local\Google\Chromium\%PROFILE%\Cache\ C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\Cache\ C:\Users\%USERNAME%\AppData\Local\Google\Chromium\%PROFILE%\Application Cache\Cache\ C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\Application Cache\Cache\ C:\Users\%USERNAME%\AppData\Local\Google\Chromium\%PROFILE%\Media Cache\ C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\Media Cache\ C:\Users\%USERNAME%\AppData\Local\Google\Chromium\%PROFILE%\GPUCache\ C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\%PROFILE%\GPUCache\ 
The Chrome Cache contains different files with the following file names:
index
data_#; where # contains a decimal digit.
f_######; where # contains a hexadecimal digit.
History
Chrome stores the history of visited sites in a file named History. This file uses the SQLite database format.
The History file can be found in same location as the Preferences file.
There is also Archived History that predates information in the History file. Note that the Archived History only contains visits.
Timestamps
The History file uses the different timestamps.
visits.visit_time
The visits.visit_time is in (the number of) microseconds since January 1, 1601 UTC
Some Python code to do the conversion into human readable format:
date_string = datetime.datetime( 1601, 1, 1 ) + datetime.timedelta( microseconds=timestamp ) 
Note that this timestamp is not the same as a Windows filetime which is (the number of) 100 nanoseconds since January 1, 1601 UTC
downloads.start_time
The downloads.start_time is in (the number of) seconds since January 1, 1970 UTC
Some Python code to do the conversion into human readable format:
date_string = datetime.datetime( 1970, 1, 1 ) + datetime.timedelta( seconds=timestamp ) 
Example queries
Some example queries:
To get an overview of the visited sites:
SELECT datetime(((visits.visit_time/1000000)-11644473600), "unixepoch"), urls.url, urls.title FROM urls, visits WHERE urls.id = visits.url; 
Note that the visit_time conversion looses precision.
To get an overview of the downloaded files:
SELECT datetime(downloads.start_time, "unixepoch"), downloads.url, downloads.full_path, downloads.received_bytes, downloads.total_bytes FROM downloads; 
How the information of the downloaded files is stored in the database can vary per version of Chrome as of version 26:
SELECT datetime(((downloads.start_time/1000000)-11644473600), "unixepoch"), downloads.target_path, downloads_url_chains.url, downloads.received_bytes, downloads.total_bytes \ FROM downloads, downloads_url_chains WHERE downloads.id = downloads_url_chains.id; 
Autofill
Chrome stores previous filled in form values a file named Web Data. This file uses the SQLite database format.
The Web Data file can be found in same location as the Preferences file.
Cookies
Chrome stores the cookies in a file named Cookies. This file uses the SQLite database format.
Extension Cookies
Chrome stores the cookies used by extensions in a file named Extension Cookies. This file uses the SQLite database format.
SELECT datetime(((cookies.creation_utc/1000000)-11644473600), "unixepoch"), cookies.host_key, cookies.name, cookies.value, cookies.path, \ datetime(((cookies.expires_utc/1000000)-11644473600), "unixepoch"), cookies.secure, cookies.httponly, datetime(((cookies.last_access_utc/1000000)-11644473600), "unixepoch"), \ cookies.has_expires, cookies.persistent, cookies.priority FROM cookies; 
Extensions
Chrome extensions are stored under user data directory in the extensions folder.
On Linux
/home/$USER/.config/google-chrome/Default/Extensions/ /home/$USER/.config/google-chrome-beta/Default/Extensions/ /home/$USER/.config/chromium/Default/Extensions/ 
On MacOS-X
/Users/$USER/Library/Application Support/Google/Chrome/Default/Extensions/ /Users/$USER/Library/Application Support/Chromium/Default/Extensions/ /Users/$USER/Library/Application Support/Google/Chrome Canary/Default/Extensions/ 
On Windows XP
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Google\Chrome\User Data\Default\Extensions\ C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Chromium\User Data\Default\Extensions\ C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Google\Chrome SxS\User Data\Default\Extensions\ 
On Windows Vista and later
C:\Users\%USERNAME%\AppData\Local\Google\Chrome\User Data\Default\Extensions\ C:\Users\%USERNAME%\AppData\Local\Chromium\User Data\Default\Extensions\ C:\Users\%USERNAME%\AppData\Local\Google\Chrome SxS\User Data\Default\Extensions\ 
Extension Activity database
Chrome, presumably as of version 29 4, stores exension activity in a file named Extension Activity. This file uses the SQLite database format.
It can be turned on by running:
./google-chrome --enable-extension-activity-logging 
Query to get most of the relevant data:
SELECT datetime(((time/1000000)-11644473600), "unixepoch"), extension_id, action_type, api_name, args, page_url, page_title, arg_url, other, activity_id FROM activitylog_uncompressed; 
The time span of the data tracked seems to be limited to a couple of days but can be useful in troubleshooting extension behavior.
Plugins
In the browser, you can view the plugins accessible by Chrome (and where on the filesystem they reside) here:
chrome://plugins/ 
Common Plugin install paths:
On Linux
/opt/google/chrome /home/$USER/.config/ 
On MacOS-X
/Library/Internet Plug-Ins/ /Users/$USER/Library/Internet Plug-Ins/ 
On Windows
??? 
Plugins added through an extension will reside inside the extension installation path.
Visited Link
In order to store which link was visited (and color them purple when links are rendered), Chrome uses the file Visited Links in the profile directory.
The file starts with header (magic : " VLnk ") followed by a list of URL fingerprints. No timing information is saved.
A URL fingerprint is computed the following way: first 8 bytes of MD5( SALT + URL ). SALT is at offset 0x10 in the header.
The table is zero'ed if the user clears browsing history, and is not updated in Private Mode.
TODO Explain discrepancies between the browsing history and this file.
Chromium-based Browsers
Chromium is a free and open-source web browser project, principally developed and maintained by Google. This codebase provides the vast majority of code for the Google Chrome browser, which is proprietary software and has some additional features.
There are many other browsers that are based on the The Chromium codebase. This section provides locations on disk of the user data for several of those browsers: Brave, Chromium, Yandex, Opera, Edge and EdgeBeta.
On Linux
/home/$USER/.config/BraveSoftware/Brave-Browser/ /home/$USER/.config/chrome-remote-desktop/chrome-config/google-chrome/ /home/$USER/.config/chrome-remote-desktop/chrome-profile/ /home/$USER/.config/chromium/ /home/$USER/.config/google-chrome-beta/ /home/$USER/.config/google-chrome/ /home/$USER/.config/opera/ /home/$USER/.config/yandex-browser-beta/ /home/$USER/snap/chromium/common/chromium/ 
On MacOS-X
/Users/$USER/Library/Application Support/BraveSoftware/Brave-Browser/ /Users/$USER/Library/Application Support/Chromium/ /Users/$USER/Library/Application Support/Google/Chrome Canary/ /Users/$USER/Library/Application Support/Google/Chrome/ /Users/$USER/Library/Application Support/Microsoft Edge Beta/ /Users/$USER/Library/Application Support/Microsoft Edge/ /Users/$USER/Library/Application Support/Yandex/YandexBrowser/ /Users/$USER/Library/Application Support/com.operasoftware.Opera/ 
On Windows
%APPDATA%\Opera Software\Opera Stable\ %APPDATA%\Brave\ %LOCALAPPDATA%\Chromium\ %LOCALAPPDATA%\Google\Chrome SxS\ %LOCALAPPDATA%\Google\Chrome\ %LOCALAPPDATA%\Microsoft\Edge Beta\ %LOCALAPPDATA%\Microsoft\Edge\ %LOCALAPPDATA%\Yandex\YandexBrowser\ 
See Also
Chrome Disk Cache Format
SQLite database format
External Links
Wikipedia article on Google Chrome
The Chromium Projects - User Data Directory
Chrome Disk Cache
Chrome User Agent strings
Google Chrome Forensics, by Kristinn Guðjónsson, January 21, 2010
Cashing in on the Google Chrome Cache, John Lehr, February 24, 2013
History Index files removed from Chrome v30, by Ryan Benson, October 2, 2013
The Chrome history was cleared! Now what?, by Ryan Benson, May 1, 2015
Evolution of Chrome Databases, by Ryan Benson, November 12, 2013
Chromebook Forensics, by Dexter Morgan, April 30, 2015
The Chromium Projects - Configuring Other Preferences
Tools
Free Tools
Chromensics
Open Source
Hindsight
Plaso