* Google release 3.0 version of Chrome for PCs
* Stable Mac version of Chrome by end of year
* Google hopes to double browser share every year
SAN FRANCISCO, Sept 15 (Reuters) - Google Inc (GOOG.O) has rolled out a new version of its Chrome Web browser and a version of the Mac browser for mainstream users will be available within months, as the company moves to double Chrome's market share.
Almost exactly one year into Google's high-profile entry into the browser market dominated by Microsoft Corp (MSFT.O), the Internet search giant is a distant No. 4, with a market share of roughly 2.8 percent.
For Google, Chrome is more than simply a browser, but part of a grand strategy to create a new Web-based operating system that could one day challenge Microsoft's control of the computer software market.
The Internet search company is readying a battery of updates, along with efforts to forge new distribution partnerships it hopes will soon make Chrome a much more significant player.
"If at the two-year birthday we're not at at least 5 percent (market share), I will be exceptionally disappointed. And if at the three year birthday we're not at 10 percent, I will be exceptionally disappointed," Chrome Engineering Director Linus Upson said.
He noted the internal goals are even more aggressive than doubling share every year.
A much-anticipated Mac version of Chrome, currently only available for testing, will be released by the year's end, Google Product Management Vice President Sundar Pichai said recenlty during the same interview with Reuters at Google's headquarters in Mountain View, California.
Version 3.0 of Chrome for PCs, released on Tuesday, brings improvements to the browser's interface, including faster performance and "themes" that allow users to customize how the browser looks.
Analysts say Chrome's focus on performance has won it fans among the technologically savvy, but say the company needs to do more as it strives to broaden the product's appeal beyond the 30 million users Google currently claims.
"For people that care about it (speed), they've already made that switch," said Forrester Research analyst Sheri McLeish. "By and large, it's a high hurdle to get people to pick-up and change technology they've been using for a while."
According to market research firm Net Applications, Internet Explorer had roughly 67 percent of the worldwide browser market in August, while the Mozilla foundation's Firefox had 23 percent and Apple Inc's (AAPL.O) Safari browser had 4 percent.
The fact that Microsoft's Internet Explorer comes pre- installed on Windows PCs is another key obstacle facing Chrome, said Gartner analyst Ray Valdes.
Google recently signed a deal with Sony Corp (6758.T) to pre-install Chrome on certain Sony PCs, allowing it to reach a potentially new pool of users. Pichai said Google is talking with all the major PC manufacturers about similar deals, although he declined to provide any details.
While the Chrome browser does not contribute any revenue to Google -- which generated nearly $22 billion in revenue last year -- the product plays an important strategic role at the company.
In addition to Google's oft-cited credo that anything that improves the online experience will ultimately benefit its Internet advertising business, Google also sees Chrome as an important plank in developing online software such as email and word processing, which it refers to as "Apps," or applications. The software is free to consumers, but Google sells enterprise- grade versions to corporations. (Reporting by Alexei Oreskovic; editing by Andre Grenon)