📺 Move fullscreen web content to a new Activity.

chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
index 8b268641cb971c61b356fa0e7a3ce6e7b3a18e5b..63fa73c80da9307e38357fe1caf098cfdaf3d829 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
@@ -2184,4 +2184,12 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
      * in this call, including showing 2D UI that was hidden.
      */
     public void onExitVR() {}
+
+    /**
+     * Whether this Activity supports moving a {@link Tab} to the
+     * {@link FullscreenWebContentsActivity} when it enters fullscreen.
+     */
+    public boolean supportsFullscreenActivity() {
+        return false;
+    }
 }