WindowManager: Send layer priority hint to SurfaceFlinger

Basic algorithm:
if (!isFocused && preferredModeId > 0) -> priority is 2
if (isFocused && preferredModeId == 0) -> priority is 1
if (isFocused && preferredModeId > 0) -> priority is 0
else priority is INT_MAX

See go/sf-generalizing-refresh-rate for master doc, and
https://docs.google.com/document/d/1ozR7UT3AZclsJ6f4NJ4WXYO2eb-GRdv-Q55AYTltZSo
for WM specific document.

Test: Device starts. Observe logs for errors.
Test: Observe printouts on SF side to make sure the correct number gets passed along.
Test: Unit tests for setting priority on Transaction.
Test: Swappy and Messaging app running in split screen. If swappy in focus,
      it gets priority 0, otherwise 2. If Messsging app in focus it gets priority 1,
      otherwise INT_MAX.
Test: Chrome playing video. Chrome Activity gets priority 0.
Test: Expand status bar. Status bar has priority 1.
Test: Application running. Status bar gets an update. Nothing is passed along.

Bug: 142507166
Change-Id: Iea75f63882b173fad089cd4a32a4831b92206797

1 files changed, 15 insertions, 0 deletions

diff --git a/core/java/android/view/SurfaceControl.java b/core/java/android/view/SurfaceControl.java
index ff8455ab0915..cc4278bdd2b6 100644
--- a/core/java/android/view/SurfaceControl.java
+++ b/core/java/android/view/SurfaceControl.java
@@ -122,6 +122,8 @@ public final class SurfaceControl implements Parcelable {
     private static native void nativeSetColor(long transactionObj, long nativeObject, float[] color);
     private static native void nativeSetFlags(long transactionObj, long nativeObject,
             int flags, int mask);
+    private static native void nativeSetFrameRateSelectionPriority(long transactionObj,
+            long nativeObject, int priority);
     private static native void nativeSetWindowCrop(long transactionObj, long nativeObject,
             int l, int t, int r, int b);
     private static native void nativeSetCornerRadius(long transactionObj, long nativeObject,
@@ -2245,6 +2247,19 @@ public final class SurfaceControl implements Parcelable {
         }
 
         /**
+         * This information is passed to SurfaceFlinger to decide which window should have a
+         * priority when deciding about the refresh rate of the display. All windows have the
+         * lowest priority by default.
+         * @hide
+         */
+        @NonNull
+        public Transaction setFrameRateSelectionPriority(@NonNull SurfaceControl sc, int priority) {
+            sc.checkNotReleased();
+            nativeSetFrameRateSelectionPriority(mNativeObject, sc.mNativeObject, priority);
+            return this;
+        }
+
+        /**
          * Request that a given surface and it's sub-tree be shown.
          *
          * @param sc The surface to show.