Get a list of available Content Providers

List<ProviderInfo> providers = getContext().getPackageManager()
    .queryContentProviders(null, 0, 0);

lists all content providers available to you on this device.

Or, if you know the process name and UID of the provider, you can reduce the list by specifying those two parameters. I have used this before to check the existence of my own content providers, more specifically those of previous (free vs. paid) installations:

List<ProviderInfo> providers = getContext().getPackageManager()
    .queryContentProviders("com.mypackage", Process.myUid(), 0);

Note the android.os.Process.myUid() to get my own process's user ID.

It should be possible by calling PackageManager.getInstalledPackages() with GET_PROVIDERS.

EDIT: example:

    for (PackageInfo pack : getPackageManager().getInstalledPackages(PackageManager.GET_PROVIDERS)) {
        ProviderInfo[] providers = pack.providers;
        if (providers != null) {
            for (ProviderInfo provider : providers) {
                Log.d("Example", "provider: " + provider.authority);
            }
        }
    }

From the command line, run:

adb shell dumpsys | grep Provider{

Note the opening brace. This will give you a short list of all the providers installed through various packages.

I used adb shell command like this $ adb shell dumpsys > dumpsys.txt and search for content providers string in the output file. From that i can see the list of content providers in the device/emulator.