It's Run that actually starts a Browser, not NewContext. If the browser
is closed or crashes, the browser handler will fail to read from the
websocket, and its goroutines will stop.
However, the target handler's goroutines may not stop. The browser
handler uses a separate cancel function to stop itself when encountering
a websocket error, so that doesn't propagate to the original context
children, like the target handler.
To fix this, make it so that NewContext can keep the cancel function
around, for Run to use it in this scenario. And add a test case that
tests this very edge case, which used to time out before the fix.
Fixes#289.
Chrome already starts with a blank page, so use that for the first
target context instead of creating a new tab.
Add the first version of the Targets API, which is useful to test this
feature.
Fixes#291.
This way, the simple examples and tests don't need to do that
separately. Practically all users will want this cleanup work to be
synchronous, and practically all Go APIs are synchronous by default, so
this makes chromedp easier to use.
First, collapse Browser.Start with NewBrowser. There's no reason to
split them up.
Second, unexport Browser.userDataDir, since it's only needed for a test.
It's also a bad precedent, as only the ExecAllocator will control the
user data directory.
Third, export Context.Browser, since we were already exporting
Context.Allocator.
Finally, remove the Executor interface, a duplicate of cdp.Executor.
Use a single websocket connection per browser, removing the need for an
extra websocket connection per target.
This is thanks to the Target.sendMessageToTarget command to send
messages to each target, and the Target.receivedMessageFromTarget event
to receive messages back.
The browser handles activity via a single worker goroutine, and the same
technique is used for each target. This means that commands and events
are dealt with in order, and we can do away with some complexity like
mutexes and extra go statements.
First, we want all of the functionality in a single package; this means
collapsing whatever is useful into the root chromedp package.
The runner package is being replaced by the Allocator interface, with a
default implementation which starts browser processes.
The client package doesn't really have a place in the new design. The
context, allocator, and browser types will handle the connection with
each browser.
Finally, the new API is context-based, hence the addition of context.go.
The tests have been modified to build and run against the new API.
