This is the second attempt to submit this CL. The first attempt
regressed on app startup because RuntimeInit installed the
custom MimeMap from commonInit() which runs post-fork of the zygote,
but that was fixed by installing it pre-fork.
This CL topic moves the default MimeMap implementation to frameworks.
Libcore starts with a minimal implementation sufficient to pass
CtsLibcoreTestCases, but frameworks can inject the real implementation.
Before this CL topic, the data files and logic (MimeMapImpl) were part of
core-*.jar on device; after this CL, they instead live in framework.jar.
Tests from MimeMapTest that check behavior of that default
implementation also move to a non-libcore CTS test.
Planned work for follow-up CL:
1. Make CTS more opinionated, with a plan to assert that all of
the default mappings are present. How exactly the expectated
mapping will be bundled in CTS is still TBD.
2. Add a vendor.mime.types file (defaults to empty) where vendors
can add additional mappings; I plan to make it such that mappings
in that file are parsed last but never override any earlier
mappings, as if each mime type / file extension was prefixed
with '?'.
3. Perhaps enforce that public APIs android.webkit.MimeTypeMap
and java.net.URLConnection.getFileNameMap() behave consistently
with MimeMap.getDefault().
Test: atest CtsLibcoreTestCases
Test: atest CtsMimeMapTestCases
Test: Checked that CtsLibcoreTestCases still passes on a build that
is missing the MimeMap.setDefault() call from RuntimeInit.java.
Test: Checked that app startup time does not regress as part of this
CL topic - see http://b/136256059#comment17
Bug: 136256059
Change-Id: I716914bf1a7e6205e539f0551f010615dacb17a8
878c77b704