Exposing some private methods to easily customize arrow popup

Change-Id: I6f6dc0604a616f26c0879732a0237767ddbfdccc
diff --git a/src/com/android/launcher3/BaseActivity.java b/src/com/android/launcher3/BaseActivity.java
index a4b6f5b..eca280b 100644
--- a/src/com/android/launcher3/BaseActivity.java
+++ b/src/com/android/launcher3/BaseActivity.java
@@ -26,6 +26,7 @@
 import android.content.Intent;
 import android.content.res.Configuration;
 import android.support.annotation.IntDef;
+import android.view.ContextThemeWrapper;
 import android.view.View.AccessibilityDelegate;
 
 import com.android.launcher3.DeviceProfile.OnDeviceProfileChangeListener;
@@ -116,13 +117,6 @@
         return Utilities.ATLEAST_NOUGAT && isInMultiWindowMode();
     }
 
-    public static BaseActivity fromContext(Context context) {
-        if (context instanceof BaseActivity) {
-            return (BaseActivity) context;
-        }
-        return ((BaseActivity) ((ContextWrapper) context).getBaseContext());
-    }
-
     public SystemUiController getSystemUiController() {
         if (mSystemUiController == null) {
             mSystemUiController = new SystemUiController(getWindow());
@@ -259,4 +253,14 @@
         writer.println(" mActivityFlags: " + mActivityFlags);
         writer.println(" mForceInvisible: " + mForceInvisible);
     }
+
+    public static <T extends BaseActivity> T fromContext(Context context) {
+        if (context instanceof BaseActivity) {
+            return (T) context;
+        } else if (context instanceof ContextThemeWrapper) {
+            return fromContext(((ContextWrapper) context).getBaseContext());
+        } else {
+            throw new IllegalArgumentException("Cannot find BaseActivity in parent tree");
+        }
+    }
 }