SkiaRenderer WebView: Add lost context error log

Change-Id: Ie1d9dadc454b36fdd4bf1c3f07e336fd49536f69
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1872739Reviewed-by: Jonathan Backer <backer@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Jonathan Backer <backer@chromium.org>
Commit-Queue: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707906}

android_webview/browser/gfx/skia_output_surface_dependency_webview.cc

@@ -123,6 +123,7 @@ void SkiaOutputSurfaceDependencyWebView::DidLoseContext(
     gpu::error::ContextLostReason reason,
     const GURL& active_url) {
   // No GpuChannelManagerDelegate here, so leave it no-op for now.
+  LOG(ERROR) << "SkiaRenderer detected lost context.";
 }
 
 }  // namespace android_webview