Bug 1770199 - Remove the nsDeviceContextSpecWin::GetDPI override. r=bobowen

The default value for the pref print.default_dpi in StaticPrefList.yaml is
already 144. Having this override simply prevents that pref from working on
Windows.

Differential Revision: https://phabricator.services.mozilla.com/D146828

widget/windows/nsDeviceContextSpecWin.cpp

@@ -334,15 +334,6 @@ already_AddRefed<PrintTarget> nsDeviceContextSpecWin::MakePrintTarget() {
   return nullptr;
 }
 
-float nsDeviceContextSpecWin::GetDPI() {
-  if (mOutputFormat == nsIPrintSettings::kOutputFormatPDF || mPrintViaSkPDF) {
-    return nsIDeviceContextSpec::GetDPI();
-  }
-  // To match the previous printing code we need to return 144 when printing to
-  // a Windows surface.
-  return 144.0f;
-}
-
 float nsDeviceContextSpecWin::GetPrintingScale() {
   MOZ_ASSERT(mPrintSettings);
   if (mOutputFormat == nsIPrintSettings::kOutputFormatPDF || mPrintViaSkPDF) {

widget/windows/nsDeviceContextSpecWin.h

@@ -36,8 +36,6 @@ class nsDeviceContextSpecWin : public nsIDeviceContextSpec {
   NS_IMETHOD Init(nsIWidget* aWidget, nsIPrintSettings* aPS,
                   bool aIsPrintPreview) override;
 
-  float GetDPI() final;
-
   float GetPrintingScale() final;
   gfxPoint GetPrintingTranslate() final;