android: add Java-side support for browser compositor async readback

ui/android/java/src/org/chromium/ui/base/WindowAndroid.java

Index: ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
diff --git a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
index 4a68dea73363a0aeaf0eb46ead8c000781be06ea..424b566ed2430ff1863b524d0c67ca69aafd8a7a 100644
--- a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
+++ b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
@@ -279,15 +279,6 @@ public class WindowAndroid {
         return mNativeWindowAndroid;
     }
 
-    /**
-     * Returns a PNG-encoded screenshot of the the window region at (|windowX|,
-     * |windowY|) with the size |width| by |height| pixels.
-     */
-    @CalledByNative
-    public byte[] grabSnapshot(int windowX, int windowY, int width, int height) {
-        return null;
-    }
-
     private native long nativeInit(long vsyncPeriod);
     private native void nativeOnVSync(long nativeWindowAndroid, long vsyncTimeMicros);
     private native void nativeDestroy(long nativeWindowAndroid);