Add a new command to get HeapSnapshot for ChromeDriver.

[gaoshuotao]

Main changes:

1. Add a new command "-chromium-take-heap-snapshot" and a new interface "TakesHeapSnapshot".
2. Make ChromeDriver.java implement "TakesHeapSnapshot".
3. Add an augmenter provider "AddTakesHeapSnapshot".

[jleyba]

This is not a standard capability and should be hidden behind a vendor prefix: -chromium-takesHeapSnapshot

[jleyba]

I'm not comfortable with extending the core Selenium API for a browser-specific feature. Can this be provided as utility library that uses WebDriver as a collaborator? Maybe something like:

WebDriver driver = // ...
HeapSnapshot snapshot = HeapSnapshotter.for(driver).takeSnapshot();

[klepikov]

Sorry, has this ever made it into the client API?

[ddavison]

@klepikov no it's not. you can do a File search by pressing T then searching for the class that the OP gave. HeapSnapshot didn't pop up.

[klepikov]

@jleyba @gaoshuotao Is there a disagreement in principle, or is it simply a case of a stalled code review?

[AutomatedTester]

@klepikov This should be handled as a 3rd party dependency and shouldnt be added to the Selenium project.

This can be in the same library as #168

[andreastt]

@gaoshuotao, do you want to address @jleyba's issues?

[lukeis]

closing, PR now too old, required changes. Submit a new PR if appropriate.