Unit Test for WebView animating in and out of screen

android_webview/browser/browser_view_renderer.cc

Index: android_webview/browser/browser_view_renderer.cc
diff --git a/android_webview/browser/browser_view_renderer.cc b/android_webview/browser/browser_view_renderer.cc
index ea9d60312836a4a3c45dc9dd20850bf05028defd..2d8581322c2e658fd881def3b113cbd5b2dc2ba6 100644
--- a/android_webview/browser/browser_view_renderer.cc
+++ b/android_webview/browser/browser_view_renderer.cc
@@ -216,6 +216,12 @@ bool BrowserViewRenderer::OnDrawHardware() {
     return false;
   }
 
+  if (last_on_draw_global_visible_rect_.IsEmpty()) {
+    // WebView could be offscreen. Need to make sure WebView invalidates when
+    // it is animated into the screen again.
+    shared_renderer_state_.SetForceInvalidateOnNextDrawGLOnUI(true);
+  }
+
   ReturnResourceFromParent();
   if (shared_renderer_state_.HasCompositorFrameOnUI()) {
     TRACE_EVENT_INSTANT0("android_webview",