Support launching home activity on secondary display

- Add a new flag indicating that the display should show
  system decorations, such as status bar, nav bar, home and IME.
- Automatically launches home activity on secondary display
  if the display support system decorations and home
  activity has multiple instances supports.
- Remove ActivityStackSupervisor#mHomeStack and move several
  home stack related methods to ActivityDisplay.

Bug: 111363427
Test: atest ActivityManagerMultiDisplayTests
      atest com.android.server.am
      Manual test on virtual display and chromecast

Change-Id: I48fe245ad12965a19a6768f5dbb4e974ce94b01a

1 files changed, 22 insertions, 0 deletions

diff --git a/core/java/android/view/Display.java b/core/java/android/view/Display.java
index 4d96fc3175cd..719a401ce0cf 100644
--- a/core/java/android/view/Display.java
+++ b/core/java/android/view/Display.java
@@ -221,6 +221,18 @@ public final class Display {
     public static final int FLAG_CAN_SHOW_WITH_INSECURE_KEYGUARD = 1 << 5;
 
     /**
+     * Display flag: Indicates that the display should show system decorations.
+     * <p>
+     * This flag identifies secondary displays that should show system decorations, such as status
+     * bar, navigation bar, home activity or IME.
+     * </p>
+     *
+     * @see #supportsSystemDecorations
+     * @hide
+     */
+    public static final int FLAG_SHOULD_SHOW_SYSTEM_DECORATIONS = 1 << 6;
+
+    /**
      * Display flag: Indicates that the contents of the display should not be scaled
      * to fit the physical screen dimensions.  Used for development only to emulate
      * devices with smaller physicals screens while preserving density.
@@ -874,6 +886,16 @@ public final class Display {
     }
 
     /**
+     * Returns whether this display should support showing system decorations.
+     *
+     * @see #FLAG_SHOULD_SHOW_SYSTEM_DECORATIONS
+     * @hide
+     */
+    public boolean supportsSystemDecorations() {
+        return (mDisplayInfo.flags & FLAG_SHOULD_SHOW_SYSTEM_DECORATIONS) != 0;
+    }
+
+    /**
      * Returns the display's HDR capabilities.
      *
      * @see #isHdr()