Design Documents

Start Here: Background Reading

Multi-process Architecture: Describes the high-level architecture of Chromium
Note: Most of the rest of the design documents assume familiarity with the concepts explained in this document.
How Blink works is a high-level overview of Blink architecture.
The "Life of a Pixel" talk (slides / video) is an introduction to Chromium's rendering pipeline, tracing the steps from web content to displayed pixels.
[somewhat outdated] How Chromium Displays Web Pages: Bottom-to-top overview of how WebKit is embedded in Chromium

Conventions and patterns for multi-platform development
Extension Security Architecture: How the extension system helps reduce the severity of extension vulnerabilities
HW Video Acceleration in Chrom{e,ium}{,OS}
Inter-process Communication: How the browser, renderer, and plugin processes communicate
Multi-process Resource Loading: How pages and images are loaded from the network into the renderer
Plugin Architecture
Process Models: Our strategies for creating new renderer processes
Profile Architecture
SafeBrowsing
Sandbox
Security Architecture: How Chromium's sandboxed rendering engine helps protect against malware
Startup
Threading: How to use threads in Chromium

Also see the documentation for V8, which is the JavaScript engine used within Chromium.

UI Development Practices: Best practices for UI development inside and outside of Chrome's content areas.
Views framework: Our UI layout layer used on Windows/Chrome OS.
views Windowing system: How to build dialog boxes and other windowed UI using views.
Aura: Chrome's next generation hardware accelerated UI framework, and the new ChromeOS window manager built using it.
NativeControls: using platform-native widgets in views.
Focus and Activation with Views and Aura.

Graphics

Network stack

Security

See also the documentation for GYP, which is the build script generation tool.

about:conflicts
Accessibility: An outline of current (and coming) accessibility support.
Auto-Throttled Screen Capture and Mirroring
Browser Window
Chromium Print Proxy: Enables a cloud print service for legacy printers and future cloud-aware printers.
Constrained Popup Windows
Desktop Notifications
DirectWrite Font Cache for Chrome on Windows
DNS Prefetching: Reducing perceived latency by resolving domain names before a user tries to follow a link
Download Page (Material Design Refresh)
Embedding Flash Fullscreen in the Browser Window
Extensions: Design documents and proposed APIs.
Find Bar
Form Autofill: A feature to automatically fill out an html form with appropriate data.
Geolocation: Adding support for W3C Geolocation API using native WebKit bindings.
IDN in Google Chrome
IndexedDB (early draft)
Info Bars
Installer: Registry entries and shortcuts
Instant
Isolated Sites
Linux Resources and Localized Strings: Loading data resources and localized strings on Linux.
Media Router & Web Presentation API
Memory Usage Backgrounder: Some information on how we measure memory in Chromium.
Mouse Lock
Omnibox Autocomplete: While typing into the omnibox, Chromium searches for and suggests possible completions.

HistoryQuickProvider: Suggests completions from the user's historical site visits.

Omnibox/IME Coordination
Ozone Porting Abstraction
Password Form Styles that Chromium Understands
Password Generation
Pepper plugin implementation
Plugin Power Saver
Preferences
Prerender
Print Preview
Printing
Rect-based event targeting in views: Making it easier to target views elements with touch.
Replace the modal cookie prompt
SafeSearch
Sane Time: Determining an accurate time in Chrome
Secure Web Proxy
Service Processes
Site Engagement: Tracking user engagement with sites they use.
Site Isolation: In-progress effort to improve Chromium's process model for security between web sites.
Software Updates: Courgette
Sync
Tab Helpers
Tab to search: How to have the Omnibox automatically provide tab to search for your site.
Tabtastic2 Requirements
Temporary downloads
Time Sources: Determining the time on a Chrome OS device
TimeTicks: How our monotonic timer, TimeTicks, works on different OSes
UI Mirroring Infrastructure: Describes the UI framework in ChromeViews that allows mirroring the browser UI in RTL locales such as Hebrew and Arabic.
UI Localization: Describes how localized strings get added to Chromium.
User scripts: Information on Chromium's support for user scripts.
Video
WebSocket: A message-oriented protocol which provides bidirectional TCP/IP-like communication between browsers and servers.

Design doc: mostly still relevant but some parts have been revised. In particular, mojo is used for the communication between Blink and //content now.
WebSocket handshake: The HTTP-like exchange before switching to WebSocket-style framing in more detail.
Obsolete design doc: WebSocket code has been drastically refactored. Most of the code described in this doc is gone. It is mostly only of historical interest.