Google Chrome
Development Stories

Tony Chang

Google, Inc.

What is Chrome?

Google Chrome is a multi-process web browser that uses the WebKit rendering engine.

WebKit is a rendering engine that parses HTML. It is used to power many applications like Safari, Dashboard, Mail, and Google Chrome.

Why multiple processes?

Browser process

• UI: tab strip, omnibox, menus
• History
• Network
• Manage other processes
• ie., the browser's "chrome"

Renderer process

• Turns HTML into something displayed on the screen
• Image decoding

Task Manager

Chrome comes with a task manager that you can use to see the processes that are being used.

Process separation

• Try to put each tab into a separate renderer process as often as possible.
• Most of the time, each tab is it's own process and when you navigate a tab to a new domain, it spins up a new process.
• Navigating to a page in the same site or opening a tab in the same site uses the same process. Example
• However, sometimes tabs have to share a renderer process because the pages are "connected". Example

Loading a Page

IPC

• Browser process and renderer process send messages back and forth. We call this inter-process communication.
• Well defined IPC interface: can only send pre-defined messages.
• Basically a function call across processes.

Sandbox

• No disk access
• No direct network access
• No direct clipboard access
• No access to windowing system (e.g. no X access on Linux)

Clipboard Access

File Upload

Sandbox

• The assumption is that there will be web exploitable bugs when rendering web pages. For example, bugs in zlib, libpng, libxml or in the javascript engine.
• A corrupt renderer process can still make IPC calls back to the browser, so we try to make the IPC interface resiliant.
• A corrupt renderer can still make network requests, get passwords and get clipboard contents.

Sandbox whitelisting

Try to whitelist based on user action. E.g., you can get the size of a file, but only if the user attached the file to a file upload control.

Filesize:

File Size Whitelist

Theme install

Decoding images in the browser process is risky, so we use a sandboxed utility process.

Getting Involved

• Download: google chrome
• Mac & Linux Dev versions: google chrome dev channel
• Report bugs: http://bugs.chromium.org/
• Source: http://dev.chromium.org/
• IRC: #chromium on EFnet

Credits

• WebKit open source project
• S5: A Simple Standards-Based Slide Show System
• pre3d: A JavaScript 3d Rendering Engine
• Inkscape: A Vector Graphics Editor

Commit Stats

Since Sept 2, 2008 (not including WebKit):

• Commits: 23059
• Commiters: 203
• External contributors: 50

In the last 30 days (not including WebKit):

• Commit rate: 82 commits per day
• 12975 files changed, 502437 insertions(+), 137013 deletions(-)

stats generated using git

Code Stats

• 3762 C and C++ files
• 3461 header files
• 1828 C++ files in WebKit (WebCore)
• 1744 header files in WebKit (WebCore)

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