Drop <meta-data> support for DocumentsProviders.

Prebuilts have finished migrating to new <intent-filter> based
approach.  Also update isDocumentUri() to match new definition.

Bug: 11109484
Change-Id: Ib95e2c3f5a9ff70b8d5e411f68ad49d1990dae8c
diff --git a/src/com/android/documentsui/RootsCache.java b/src/com/android/documentsui/RootsCache.java
index eb56765..b98e1ee 100644
--- a/src/com/android/documentsui/RootsCache.java
+++ b/src/com/android/documentsui/RootsCache.java
@@ -194,16 +194,6 @@
                 handleDocumentsProvider(info.providerInfo);
             }
 
-            // Pick up legacy providers
-            final List<ProviderInfo> legacyProviders = pm.queryContentProviders(
-                    null, -1, PackageManager.GET_META_DATA);
-            for (ProviderInfo info : legacyProviders) {
-                if (info.metaData != null && info.metaData.containsKey(
-                        DocumentsContract.META_DATA_DOCUMENT_PROVIDER)) {
-                    handleDocumentsProvider(info);
-                }
-            }
-
             final long delta = SystemClock.elapsedRealtime() - start;
             Log.d(TAG, "Update found " + mTaskRoots.size() + " roots in " + delta + "ms");
             synchronized (mLock) {