Mus experiment in content shell on Android.

ui/platform_window/android/java/src/org/chromium/ui/PlatformWindowAndroid.java

Index: ui/platform_window/android/java/src/org/chromium/ui/PlatformWindowAndroid.java
diff --git a/ui/platform_window/android/java/src/org/chromium/ui/PlatformWindowAndroid.java b/ui/platform_window/android/java/src/org/chromium/ui/PlatformWindowAndroid.java
index 91c7328d90fcb89a0eb6cf0100aab40eb8b47f1b..070f209c0d5c4dd10fc503e9f28a7ea269c92fe2 100644
--- a/ui/platform_window/android/java/src/org/chromium/ui/PlatformWindowAndroid.java
+++ b/ui/platform_window/android/java/src/org/chromium/ui/PlatformWindowAndroid.java
@@ -28,12 +28,19 @@ public class PlatformWindowAndroid extends SurfaceView {
     private final SurfaceHolder.Callback mSurfaceCallback;
     private final PlatformImeControllerAndroid mImeController;
 
+    private static Activity sActivity;
+
+    public static void setActivity(Activity activity) {
+        sActivity = activity;
+    }
+
     @CalledByNative
-    public static PlatformWindowAndroid createForActivity(
-            Activity activity, long nativeViewport, long nativeImeController) {
+    public static PlatformWindowAndroid createForCurrentActivity(
+            long nativeViewport, long nativeImeController) {
+        assert sActivity != null;
         PlatformWindowAndroid rv =
-                new PlatformWindowAndroid(activity, nativeViewport, nativeImeController);
-        activity.setContentView(rv);
+                new PlatformWindowAndroid(sActivity, nativeViewport, nativeImeController);
+        sActivity.setContentView(rv);
         return rv;
     }