Add LayoutHelper class.

app/src/main/java/chat/rocket/android/app/LayoutHelper.kt

+package chat.rocket.android.app
+
+import android.app.Activity
+import android.graphics.Rect
+import android.view.View
+import android.widget.FrameLayout
+
+/**
+ * @author Filipe de Lima Brito (filipedelimabrito@gmail.com)
+ */
+//TODO Check if this code has memory leak.
+object LayoutHelper {
+    private lateinit var childOfContent: View
+    private var usableHeightPrevious: Int = 0
+    private lateinit var frameLayoutParams: FrameLayout.LayoutParams
+
+    /**
+     * Workaround to adjust the layout when in the full screen mode.
+     *
+     * The original author of this code is Joseph Johnson and you can see his answer here: https://stackoverflow.com/a/19494006/4744263
+     *
+     * Note that this function has some differences from the original, like using *frameLayoutParams.height = usableHeightNow* instead of
+     * *frameLayoutParams.height = usableHeightSansKeyboard* (RobertoAllende's comment - from the same link above).
+     *
+     * @param activity The Activity to adjust the layout.
+     */
+    fun androidBug5497Workaround(activity: Activity) {
+        val content = activity.findViewById<View>(android.R.id.content) as FrameLayout
+        childOfContent = content.getChildAt(0)
+        childOfContent.viewTreeObserver.addOnGlobalLayoutListener({ resizeChildOfContent() })
+        frameLayoutParams = childOfContent.layoutParams as FrameLayout.LayoutParams
+    }
+
+    private fun resizeChildOfContent() {
+        val usableHeightNow = computeUsableHeight()
+        if (usableHeightNow != usableHeightPrevious) {
+            val usableHeightSansKeyboard = childOfContent.rootView.height
+            val heightDifference = usableHeightSansKeyboard - usableHeightNow
+            if (heightDifference > usableHeightSansKeyboard / 4) {
+                // keyboard probably just became visible
+                frameLayoutParams.height = usableHeightSansKeyboard - heightDifference
+            } else {
+                // keyboard probably just became hidden
+                frameLayoutParams.height = usableHeightNow
+            }
+            childOfContent.requestLayout()
+            usableHeightPrevious = usableHeightNow
+        }
+    }
+
+    private fun computeUsableHeight(): Int {
+        val rect = Rect()
+        childOfContent.getWindowVisibleDisplayFrame(rect)
+        return rect.bottom - rect.top
+    }
+}
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