[printing] Set the error if |settings| is null

If mojom::PrintManagerHost is disconnected in the browser after
calling UpdatePrintSettings() in the renderer, |settings| could
be null.

This CL sets the error if |settings| could be null after
UpdatePrintSettings().

Bug: 1151870
Change-Id: I7145212f495d2d9304dd588998cd54bc96ecce2c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2560016Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Julie Kim <jkim@igalia.com>
Cr-Commit-Position: refs/heads/master@{#832175}

components/printing/renderer/print_render_frame_helper.cc

@@ -2202,6 +2202,14 @@ bool PrintRenderFrameHelper::UpdatePrintSettings(
   bool canceled = false;
   GetPrintManagerHost()->UpdatePrintSettings(cookie, job_settings->Clone(),
                                              &settings, &canceled);
+
+  // If mojom::PrintManagerHost is disconnected in the browser after calling
+  // UpdatePrintSettings(), |settings| could be null.
+  if (!settings) {
+    print_preview_context_.set_error(PREVIEW_ERROR_EMPTY_PRINTER_SETTINGS);
+    return false;
+  }
+
   if (canceled) {
     notify_browser_of_print_failure_ = false;
     return false;

components/printing/renderer/print_render_frame_helper.h

@@ -187,6 +187,7 @@ class PrintRenderFrameHelper
     PREVIEW_ERROR_PAGE_RENDERED_WITHOUT_METAFILE_DEPRECATED = 6,
     PREVIEW_ERROR_INVALID_PRINTER_SETTINGS = 7,
     PREVIEW_ERROR_METAFILE_CAPTURE_FAILED_DEPRECATED = 8,
+    PREVIEW_ERROR_EMPTY_PRINTER_SETTINGS = 9,
     PREVIEW_ERROR_LAST_ENUM  // Always last.
   };
 

tools/metrics/histograms/enums.xml

@@ -60012,6 +60012,7 @@ Called by update_net_trust_anchors.py.-->
   <int value="6" label="PreviewPageRendered with no metafile (Deprecated)"/>
   <int value="7" label="Received bad printer settings"/>
   <int value="8" label="Capture metadata failed (Deprecated)"/>
+  <int value="9" label="Got empty printer settings"/>
 </enum>
 
 <enum name="PrintPreviewFontTypeType">