Screenshot by Stephen Shankland/CNET

Google today released a beta version of its Chrome browser for Android, a momentous step that marries two of Google's most important programming projects.

The new browser, unlike the stock Android browser, is available in the Android Market so that people don't have to wait for handset makers to offer it through an operating system upgrade. But its reliance on newer hardware acceleration interfaces means it only works on Ice Cream Sandwich, which despite emerging last year on Samsung's Galaxy Nexus smartphone remains a rarity in the real world.

Chrome for Android (review) includes the desktop version's V8 JavaScript engine, has gesture-based controls for moving among multiple tabs, synchronizes with the desktop version of Chrome, and shuts out plug-ins including Adobe Systems' Flash Player and Google's own Native Client. With its performance and features, Google expects Android users to increase their browser activity.

"In general, we have seen usage go up," said Sundar Pichai, Google's senior vice president of Chrome and Apps. "I expect to see more people use the mobile Web."

It's unfortunate that it's limited to Ice Cream Sandwich, but Chrome doubtless will take off widely among those with Android 4.0. Even in beta, it's a compelling browser at least on the Galaxy Nexus I tried it on, and it's and a much better match for Apple's Safari on iOS. And eventually, its success is all but assured when it simply becomes what ships with Android.

Google tried to examine every aspect of browsing and if necessary adapt it for the mobile world. "The intent was to reinvent mobile browsers," said Arnaud Weber, engineering manager for Chrome. "We went through every feature of Chrome and brainstormed every feature."

Peas in a pod

Android and Chrome are made for each other. Each arrived for the public to use in the closing months of 2008. Each started as small, rough projects that exploded in usage and became top priorities for the company.

Each project isn't actually an end in itself, but rather a means to an end: get more people to use the Internet and Google's services on it. Android and Chrome are vehicles to carry people to Google search, YouTube, Google Docs, Google Maps, Google+, and doubtless many future online services. Not coincidentally, Chrome and Android are set up to work better if you're signed into a Google account.

With so much to gain from each other, it's somewhat surprising that it took more than three years for the Chrome chocolate to get stuck in the Android peanut butter. But Google wanted to make sure Chrome for Android would be good enough, Pichai said.

screenshot by Stephen Shankland/CNET

"We really wanted to get the full capabilities of a desktop browser--stuff like V8--in a highly capable browser that's optimized for the mobile experience," Pichai said. "It was a challenge."

And Google didn't want to brand the stock Android browser with the Chrome name. It wasn't based on Chromium, the open-source foundation of Chrome, and Google wanted to ensure the "underlying mobile platform could run things you're used to in desktops," Pichai said.

Feature frenzy

Among the features in the browser:

 The browser shows multiple tabs like overlapping pages when you tap the tabs button. Swiping one of the pages to one side or the other close it in much the same way that you can sweep away notifications on Ice Cream Sandwich. Once you click a page, it expands to fill the whole screen, at which point you can switch to new pages by sliding your finger from one edge or the other.

 The browser can preload pages in advance when Google has high confidence that you'll likely tap its link. That means pages don't have to wait so much for the network.

 Chrome for Android has hardware acceleration for tasks such as scrolling. It also uses it for slick visual feedback effects like browser tabs.

 It supports a wide range of Web standards, including Web Workers for multiple computing processes, Web Sockets for fast server-browser communciations, HTML5 video and audio, and IndexedDB for offline storage.

screenshot by Stephen Shankland/CNET

 The browser is rejiggered for tablets. "On tablets, we realize consumers expect a similar experience to what they get on a laptop," Pichai said, so for example the tab strip looks like what you'd see on a personal computer.

 You can synchronize data such as bookmarks and Web address autocomplete suggestions with your desktop browser, with passwords arriving in a later upgrade. As with Firefox for Android, tabs you had open on your laptop or desktop can be opened from a list in Chrome for Android. To use sync, you must be signed into your Google account.

 The browser has incognito mode that doesn't leave traces such as cached images, cookies, and browsing history on the phone. It's walled off into a separate stack of tabs; if any incognito tabs are open, you can move between them and the ordinary stack of tabs by tapping the tab button and then tapping the appropriate stack.

 Programmers can use their PCs to remotely debug Web pages that don't work properly on Chrome for Android. A command on the PC will open the mobile browser's Web pages for scrutiny.

Web apps or native apps?

Chrome for Android increases a certain tension within Google: should software run natively on a particular computing device or as a Web app within a browser?

For Android, the answer clearly has been largely the former as Google has pushed the Android Market and worked to improve programming tools and interfaces. But part of Chrome's raison d'etre has been to spur Web-app innovation, a subject near and dear to Google's heart. Because browsers run on so many devices, Web apps span them and at least theoretically offer programmers the promise of cross-platform development.

Naturally, with Chrome on board, Android becomes a much more powerful foundation for Web applications. That's especially true since Chrome will be on the Android Market and therefore Android users will be able to upgrade it even when their handset manufacturers can't be bothered to keep up with newer Android releases.

But Chrome's arrival doesn't herald a new age when Web apps rule on Android.

"The mobile ecosystem is evolving at such a rapid pace that native apps will always be there, while the Web works its way there," Pichai said.

Chrome for Android doesn't yet overwrite the stock Android browser. The latter is still used, for example, by other Android apps that need a browser engine.

Android 4.0 only

Google stuck required Ice Cream Sandwich because it has necessary interfaces such as those for hardware acceleration. It sure is convenient, though, that it means Google doesn't have to worry about a lot of problems with compatibility and performance of a lot of older phones.

In fact, Google passing over earlier Android versions is almost exactly what Microsoft chose to do with Internet Explorer 9 when it dropped Windows XP support, in part because it lacks newer graphics interfaces. That cuts off a lot of people but simplifies engineering and support.

"ICS represesnts a big leap forward," Pichai said of Google's choice. "It made sense to aim there, to build for the future."

Likewise, don't expect Chrome on other mobile operating systems, most notably iOS. Apple permits other browsers on iOS only if they use its WebKit engine to render Web pages; although Chrome stems from the same WebKit lineage, it's a different bundle of bits with, for example, a different JavaScript engine.

"On iOS, we can't run V8 or our multiprocess architecture," Pichai said. "There are a lot of limitations."

Chrome for Android is based on Chrome 16, the current stable release of the browser for computers. Google plans to update Chrome for Android every six weeks, just like the desktop version, and eventually the browser version numbers will sync up, Pichai said.

Net Applications

"Our intent is to have the smallest possible gap" between the desktop and mobile versions of Chrome, Weber said.

Chrome for Android won't support Flash, Pichai said. Google has been a tight Flash ally with its creator, Adobe Systems, but Google was spared a tough choice when Adobe scuppered its attempt to extend Flash from desktop to mobile last year.

Google's own Native Client, for running Web apps compiled to run at native speeds, also isn't an option, said Dave Burke, the Android engineering director. For that sort of software, programmers will simply write native Android apps, he said.

But Google loves the mobile Web--and it's a big deal financially.

"We believe one in every seven searches on Google comes from a mobile device," said JP Morgan analyst Doug Anmuth in a research report yesterday.

Advertisers pay only a half to a quarter the amount for each ad when people click on them compared to what they pay on personal computers right now, but more mobile usage likely will mean more advertisers bidding and therefore higher cost-per-click payment rates for Google, he said.

But overall, a lot of Google's excitement seems to be just about finally giving a top company brand a prominent place in a fast-moving, important market.

"I think mobile browsing is in its infancy. As phones are getting more powerful, as screen sizes are getting larger and higher-resolution, and as connectivity is getting better going from 3G to 4G, I think mobile browsing can be huge," Pichai said. Now using Chrome on Android, "my browser usage has sky rocketed."