Properly set the DPI for the "Save to PDF" destination.

Currently, PrintingContext::UsePdfSettings() sets the DPI to the wrong
value, and GetPdfCapabilities() does not set it at all. Then
UpdatePrintSettings() papers over these problems and override the DPI
with the correct value.

Stop papering over the problems in UpdatePrintSettings(). Instead, just
set the DPI value correctly in the first place in the two problematic
functions mentioned above.

Change-Id: I3733a725eda26fa408c58234736f3a25967053b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3646278
Reviewed-by: Alan Screen <awscreen@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1003375}

chrome/browser/ui/webui/print_preview/pdf_printer_handler.cc

@@ -148,6 +148,13 @@ base::Value GetPdfCapabilities(
   }
   media.SaveTo(&description);
 
+  // DPI value should match PrintingContext::UsePdfSettings().
+  cloud_devices::printer::DpiCapability dpi;
+  dpi.AddDefaultOption(
+      cloud_devices::printer::Dpi(kDefaultPdfDpi, kDefaultPdfDpi),
+      /*is_default=*/true);
+  dpi.SaveTo(&description);
+
   return std::move(description).ToValue();
 }
 

chrome/browser/ui/webui/print_preview/pdf_printer_handler_unittest.cc

@@ -43,6 +43,13 @@ const char kPdfPrinterCapability[] =
                 }
               ]
             },
+            "dpi": {
+               "option": [ {
+                  "horizontal_dpi": 300,
+                  "is_default": true,
+                  "vertical_dpi": 300
+               } ]
+            },
             "media_size":{
               "option":[
                 {

printing/printing_context.cc

@@ -101,8 +101,9 @@ void PrintingContext::UsePdfSettings() {
   pdf_settings.Set(kSettingCollate, true);
   pdf_settings.Set(kSettingCopies, 1);
   pdf_settings.Set(kSettingColor, static_cast<int>(mojom::ColorModel::kColor));
-  pdf_settings.Set(kSettingDpiHorizontal, kPointsPerInch);
-  pdf_settings.Set(kSettingDpiVertical, kPointsPerInch);
+  // DPI value should match GetPdfCapabilities().
+  pdf_settings.Set(kSettingDpiHorizontal, kDefaultPdfDpi);
+  pdf_settings.Set(kSettingDpiVertical, kDefaultPdfDpi);
   pdf_settings.Set(kSettingDuplexMode,
                    static_cast<int>(printing::mojom::DuplexMode::kSimplex));
   pdf_settings.Set(kSettingLandscape, false);
@@ -152,7 +153,8 @@ mojom::ResultCode PrintingContext::UpdatePrintSettings(
   if (!open_in_external_preview &&
       (printer_type == mojom::PrinterType::kPdf ||
        printer_type == mojom::PrinterType::kExtension)) {
-    settings_->set_dpi(kDefaultPdfDpi);
+    if (printer_type == mojom::PrinterType::kExtension)
+      settings_->set_dpi(kDefaultPdfDpi);
     gfx::Size paper_size(GetPdfPaperSizeDeviceUnits());
     if (!settings_->requested_media().size_microns.IsEmpty()) {
       float device_microns_per_device_unit =