Adobe’s Flash Player has come under fire from developers and companies who question its necessity, but the plug-in has just received a big vote of confidence from Google.

This week, Google announced that its Chrome browser will come with Flash built in. And Google, Adobe, and another browser maker, Mozilla, have revealed plans to improve the way plug-ins interface with browsers. This could lead to better performance, security, and user experience for Flash and other plug-ins, say those involved.

Flash is commonly used to add graphics, interactive features, video, and animation to websites. But users have to download and install Flash to make these features work, and they need to download newer versions to keep it up-to-date.

Google now plans to bundle Flash with Chrome downloads, and to make it part of Chrome’s automatic update system. This means users should always run the most recent, stable, and secure version. In the future, Google and Adobe plan to work on deeper integrated features, such as finding a way for Chrome’s unique security system to work in conjunction with Flash.

Plug-in software can add all sorts of core capabilities to a browser. Flash is the most widely used plug-in; it is installed on nearly all desktop computers and works with all major browsers. However, the plug-in has been criticized recently by developers who would prefer to see browsers use open standards, such as HTML 5, for multimedia, instead of relying on proprietary platforms like Flash. Apple’s decision to exclude Flash support from the iPhone and the iPad has also spurred efforts to develop interactive Web applications without Flash.

Some experts say that Google’s move shows that Flash still plays a vital role on the Internet.

Integrating Flash and Chrome is the beginning of a larger effort by Google, Adobe, and Mozilla to improve the way browsers and plug-ins interact. Chris Blizzard, Mozilla’s director of evangelism, explains that the current system for connecting the two evolved from the application programming interface (API) used by the Netscape browser in the late ’90s. This system is now used by every major browser except Microsoft, which has its own interface, called ActiveX. But the approach doesn’t work well with modern efforts to make browsers more responsive and reliable, Blizzard says, and a new API is needed.

For example, Google’s Chrome browser uses a security technique called sandboxing to isolate some code so that it can’t access restricted parts of memory. But Chrome plug-ins cannot follow the same system, undermining the value of sandboxing. Paul Betlem, senior director of Flash Player engineering at Adobe, says his company and Google are working on changing this. Eventually, he hopes, the same capability could be shared with other browsers.

Betlem hopes that the new API will address long-standing frustrations with the existing techniques for connecting browsers and plug-ins. For example, he says, whenever a browser gets new capabilities, such as the option to use touch input, plug-in vendors have to negotiate with each browser maker to figure out how their plug-in can access this functionality. As a result, plug-ins access a computer’s resources in a variety of ways, which can make them behave inconsistently from one browser or operating system to another.

A better interface between the browser and the plug-in, Betlem says, would make it easier for developers to create Web applications, and would result in better performance. Betlem also points to other benefits of tighter integration between plug-ins and browsers. For example, he says, the browser could share its security settings with a plug-in, so that both behave as the user expects.

“If you put this together with the work that’s being done to get Flash and Air onto Android, I think it’s clear that Google’s perspective is that a full Internet experience includes Flash support,” says Jeffrey Hammond, a principal analyst for Forrester Research. He notes that Google may see providing a good Flash experience for its users as a way to entice consumers and developers away from the iPhone.

The move also represents a pragmatic assessment of the status of HTML 5, according to Al Hilwa, program director for applications development software at research firm IDC. He notes that Google has been a strong supporter of the standard, so its current efforts with Flash suggest that HTML 5 is far from ready to substitute for popular plug-ins. “In many ways this clarifies what everyone already knows and feels,” he says.

But the new technology will not stop the development of HTML 5. Andreas Bovens, Web evangelist for the browser maker Opera, says, “In the short run, with specifications and implementations still evolving, Flash will undoubtedly be around.” In the long run, however, Bovens expects that for some areas, such as video, interactive graphs, and ad banners, Web standard technologies including HTML 5 “will trump Flash, and will be the preferred choice for developers.”