account for find dialog height when positioning layers

The Find dialog draws on top of the WebView, including any
layers attached to the bottom of the screen. Adjust the view
dimenions returned to the layer code by the height of the Find
dialog if visible.

http://b/2453769

core/java/android/webkit/WebView.java

@@ -3133,6 +3133,9 @@ public class WebView extends AbsoluteLayout
         metrics.mScrollY = computeVerticalScrollOffset();
         metrics.mWidth = getWidth();
         metrics.mHeight = getHeight() - getVisibleTitleHeight();
+        if (mFindIsUp) {
+            metrics.mHeight -= mFindHeight;
+        }
         metrics.mInvScale = mInvActualScale;
         return metrics;
     }