Adding support for PIP actions.

- Introduced generic RemoteAction to represents an action
  that can be made across processes with an icon and text
  description based on a Notification action.
- Modified PinnedStackController to ensure that it notifies
  the listeners from the source of truth, this ensures that
  SysUI is in the right state if killed and re-registers
  itself.

Test: Enable menu & minimize in SystemUI tuner.
Test: android.server.cts.ActivityManagerPinnedStackTests
Test: #testNumPipActions

Change-Id: I5b5d0cf9de3f06b5687337d59cfb91e17355bdb1
Signed-off-by: Winson Chung <winsonc@google.com>
diff --git a/packages/SystemUI/res/values/strings.xml b/packages/SystemUI/res/values/strings.xml
index c8b3b69d..6af2fc6 100644
--- a/packages/SystemUI/res/values/strings.xml
+++ b/packages/SystemUI/res/values/strings.xml
@@ -1688,9 +1688,15 @@
         not appear on production builds ever. -->
     <string name="tuner_doze_always_on" translatable="false">Always on</string>
 
-    <!-- Making the PIP fullscreen -->
+    <!-- Making the PIP fullscreen [CHAR LIMIT=25] -->
     <string name="pip_phone_expand">Expand</string>
 
+    <!-- Label for PIP action to Minimize the PIP [CHAR LIMIT=25] -->
+    <string name="pip_phone_minimize">Minimize</string>
+
+    <!-- Label for PIP action to Dismiss the PIP -->
+    <string name="pip_phone_dismiss">Dismiss</string>
+
     <!-- PIP section of the tuner. Non-translatable since it should
         not appear on production builds ever. -->
     <string name="picture_in_picture" translatable="false">Picture-in-Picture</string>