Relax auto-launch checks for GET_CONTENT.

When a developer wraps an intent with Intent.createChooser(), they're
indicating that the user should always be prompted, instead of using
any "always use" defaults.  A recent CL changed the chooser behavior
to ensure that UI is always shown in the case where there is only one
match.

However, this caused us to start prompting for the GET_CONTENT intent,
for which there is only ever one DocumentsUI system app.  Since that
app delivers on the createChooser() contract described above, we're
okay automatically launching it.

Bug: 24464358
Change-Id: I0279d3343479c134a35f41ddf3cb4204d0ae6a90
diff --git a/core/java/android/provider/DocumentsContract.java b/core/java/android/provider/DocumentsContract.java
index c7ba607..f5221c6 100644
--- a/core/java/android/provider/DocumentsContract.java
+++ b/core/java/android/provider/DocumentsContract.java
@@ -130,6 +130,9 @@
      */
     private static final int THUMBNAIL_BUFFER_SIZE = (int) (128 * KB_IN_BYTES);
 
+    /** {@hide} */
+    public static final String PACKAGE_DOCUMENTS_UI = "com.android.documentsui";
+
     /**
      * Constants related to a document, including {@link Cursor} column names
      * and flags.
diff --git a/core/java/com/android/internal/app/ChooserActivity.java b/core/java/com/android/internal/app/ChooserActivity.java
index 3219dcb..2e0bf06 100644
--- a/core/java/com/android/internal/app/ChooserActivity.java
+++ b/core/java/com/android/internal/app/ChooserActivity.java
@@ -40,6 +40,7 @@
 import android.os.ResultReceiver;
 import android.os.UserHandle;
 import android.os.UserManager;
+import android.provider.DocumentsContract;
 import android.service.chooser.ChooserTarget;
 import android.service.chooser.ChooserTargetService;
 import android.service.chooser.IChooserTargetResult;
@@ -269,7 +270,20 @@
     }
 
     @Override
-    boolean shouldAutoLaunchSingleChoice() {
+    boolean shouldAutoLaunchSingleChoice(TargetInfo target) {
+        final Intent intent = target.getResolvedIntent();
+        final ResolveInfo resolve = target.getResolveInfo();
+
+        // When GET_CONTENT is handled by the DocumentsUI system component,
+        // we're okay automatically launching it, since it offers it's own
+        // intent disambiguation UI.
+        if (intent != null && Intent.ACTION_GET_CONTENT.equals(intent.getAction())
+                && resolve != null && resolve.priority > 0
+                && resolve.activityInfo != null && DocumentsContract.PACKAGE_DOCUMENTS_UI
+                        .equals(resolve.activityInfo.packageName)) {
+            return true;
+        }
+
         return false;
     }
 
diff --git a/core/java/com/android/internal/app/ResolverActivity.java b/core/java/com/android/internal/app/ResolverActivity.java
index ef9d1ce..1710489 100644
--- a/core/java/com/android/internal/app/ResolverActivity.java
+++ b/core/java/com/android/internal/app/ResolverActivity.java
@@ -796,7 +796,7 @@
         return false;
     }
 
-    boolean shouldAutoLaunchSingleChoice() {
+    boolean shouldAutoLaunchSingleChoice(TargetInfo target) {
         return true;
     }
 
@@ -837,18 +837,21 @@
         mAlwaysUseOption = alwaysUseOption;
 
         int count = mAdapter.getUnfilteredCount();
-        if ((!shouldAutoLaunchSingleChoice() && count > 0)
-                || count > 1
-                || (count == 1 && mAdapter.getOtherProfile() != null)) {
+        if (count == 1 && mAdapter.getOtherProfile() == null) {
+            // Only one target, so we're a candidate to auto-launch!
+            final TargetInfo target = mAdapter.targetInfoForPosition(0, false);
+            if (shouldAutoLaunchSingleChoice(target)) {
+                safelyStartActivity(target);
+                mPackageMonitor.unregister();
+                mRegistered = false;
+                finish();
+                return true;
+            }
+        }
+        if (count > 0) {
             setContentView(layoutId);
             mAdapterView = (AbsListView) findViewById(R.id.resolver_list);
             onPrepareAdapterView(mAdapterView, mAdapter, alwaysUseOption);
-        } else if (count == 1) {
-            safelyStartActivity(mAdapter.targetInfoForPosition(0, false));
-            mPackageMonitor.unregister();
-            mRegistered = false;
-            finish();
-            return true;
         } else {
             setContentView(R.layout.resolver_list);