Be robust to printing too large pages in tests

content/shell/renderer/test_runner/web_test_proxy.cc

Index: content/shell/renderer/test_runner/web_test_proxy.cc
diff --git a/content/shell/renderer/test_runner/web_test_proxy.cc b/content/shell/renderer/test_runner/web_test_proxy.cc
index 0342bdd637a5d5e851793659cbe715e8d55a3099..1d107898f9efb5ae0b5bb9cec874507f20ec27f4 100644
--- a/content/shell/renderer/test_runner/web_test_proxy.cc
+++ b/content/shell/renderer/test_runner/web_test_proxy.cc
@@ -478,8 +478,11 @@ void WebTestProxyBase::CapturePixelsForPrinting(
   bool is_opaque = false;
   skia::RefPtr<SkCanvas> canvas(skia::AdoptRef(skia::TryCreateBitmapCanvas(
       page_size_in_pixels.width, totalHeight, is_opaque)));
-  if (canvas)
-    web_frame->printPagesWithBoundaries(canvas.get(), page_size_in_pixels);
+  if (!canvas) {
+    callback.Run(SkBitmap());
+    return;
+  }
+  web_frame->printPagesWithBoundaries(canvas.get(), page_size_in_pixels);
   web_frame->printEnd();
 
   DrawSelectionRect(canvas.get());