Add more logging to diagnose test.

Test if embedder WebContents has page focus when test fails.

TBR=alexmos@chromium.org

Bug: 1024672
Change-Id: Ieff2034984cd895336fa9978943c83f17cd27f6c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1934828Reviewed-by: James MacLean <wjmaclean@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718864}

chrome/browser/site_isolation/site_per_process_interactive_browsertest.cc

@@ -1299,6 +1299,10 @@ IN_PROC_BROWSER_TEST_F(SitePerProcessInteractivePDFTest,
     LOG(ERROR) << "Embedder focused frame = "
                << embedder_web_contents->GetFocusedFrame()
                << ", main frame = " << main_frame
+               << ", embedder_contents_focused = "
+               << IsRenderWidgetHostFocused(
+                      embedder_web_contents->GetRenderWidgetHostView()
+                          ->GetRenderWidgetHost())
                << ", iframe_text = " << child_text_area
                << ", iframe_pdf = " << ChildFrameAt(main_frame, 1);
   }