device pulldown not populated when there's no network connection

When I was without a network connection, I noticed that the device pulldown didn’t populate. I tracked this down to:

• the flutter daemon process was blocked on startup due to another flutter process having the startup lock (Waiting for another flutter command to release the startup lock...)
• this process was the one listing flutter samples (flutter create --list-samples)
• there were 15 sample listing processes running
• when run off-line, these process try an exponential, non-terminating attempts to connect to and download the catalog of samples
• there’s a race condition in FlutterSamplesManager that will cause new requests to fire off if the initial one hasn’t completed yet; it looks like FlutterSamplesManager.getSamples() is called several times a second and will fire off many (dozens?) of flutter create --list-samples

Download failed -- attempting retry 1 in 1 second...
Download failed -- attempting retry 2 in 2 seconds...
Download failed -- attempting retry 3 in 4 seconds...
Download failed -- attempting retry 4 in 8 seconds...
Download failed -- attempting retry 5 in 16 seconds...
Download failed -- attempting retry 6 in 32 seconds...

Concretely for flutter_tools:

• flutter create --list-samples needs to release the startup lock
• flutter create --list-samples should not re-try the download indefinitely

Instead of a command to download the samples index, we may want to change to a mechanism where the index if built on the flutter chromium bots, and included as part of the SDK. This would mirror how other sdk artifacts are provisioned.

@DanTup @pq

[devoncarew]

I think having this being just another sdk artifact makes sense. That way the samples are in-sync with the sdk you’d use to create them.

[devoncarew]

@pq, moving this into M36. There are ~2 issues in the IntelliJ code we should address, even taking into account the fix in flutter_tools:

• FlutterSamplesManager can fire start many copies of flutter create --list-samples in parallel
• FlutterSamplesManager lets the process run indefinitely (it should have a hard limit of something like 30 seconds, to account for the older flutter_tools)