MagnificationGestureHandler refactoring and unit test

This is aimed at making MagnificationGestureHandler easier to understand
and reason about

Test: provided unit test + manual magnification test
Change-Id: I958ef0bdd2e6f857a2fab24962b1a06480685732

1 files changed, 8 insertions, 0 deletions

diff --git a/core/java/android/util/ExceptionUtils.java b/core/java/android/util/ExceptionUtils.java
index 44019c32560d..da7387fcae70 100644
--- a/core/java/android/util/ExceptionUtils.java
+++ b/core/java/android/util/ExceptionUtils.java
@@ -78,4 +78,12 @@ public class ExceptionUtils {
         propagateIfInstanceOf(t, RuntimeException.class);
         throw new RuntimeException(t);
     }
+
+    /**
+     * Gets the root {@link Throwable#getCause() cause} of {@code t}
+     */
+    public static @NonNull Throwable getRootCause(@NonNull Throwable t) {
+        while (t.getCause() != null) t = t.getCause();
+        return t;
+    }
 }