Bug 1667953 p1. Stop reading printer specific settings from global prefs. r=bobowen

Differential Revision: https://phabricator.services.mozilla.com/D91819

modules/libpref/init/all.js

@@ -913,6 +913,14 @@ pref("browser.fixup.alternate.prefix", "www.");
 pref("browser.fixup.alternate.suffix", ".com");
 pref("browser.fixup.fallback-to-https", true);
 
+// NOTE: On most platforms we save print settins to prefs with the name of the
+// printer in the pref name (Android being the notable exception, where prefs
+// are saved "globally" without a printer name in the pref name).  For those
+// platforms, the prefs below simply act as default values for when we
+// encounter a printer for the first time, but only a subset of prefs will be
+// used in this case.  See nsPrintSettingsService::InitPrintSettingsFromPrefs
+// for the restrictions on which prefs can act as defaults.
+
 // Print/Preview Shrink-To-Fit won't shrink below 20% for text-ish documents.
 pref("print.shrink-to-fit.scale-limit-percent", 20);
 

widget/cocoa/nsPrintSettingsServiceX.mm

@@ -173,7 +173,17 @@ nsresult nsPrintSettingsServiceX::_CreatePrintSettings(nsIPrintSettings** _retva
     return rv;
   }
 
-  InitPrintSettingsFromPrefs(*_retval, false, nsIPrintSettings::kInitSaveAll);
+  auto globalPrintSettings =
+      nsIPrintSettings::kInitSaveShrinkToFit | nsIPrintSettings::kInitSaveHeaderLeft |
+      nsIPrintSettings::kInitSaveHeaderCenter | nsIPrintSettings::kInitSaveHeaderRight |
+      nsIPrintSettings::kInitSaveFooterLeft | nsIPrintSettings::kInitSaveFooterCenter |
+      nsIPrintSettings::kInitSaveFooterRight | nsIPrintSettings::kInitSaveEdges |
+      nsIPrintSettings::kInitSaveReversed | nsIPrintSettings::kInitSaveInColor;
+
+  // XXX Why is Mac special? Why are we copying global print settings here?
+  // nsPrintSettingsService::InitPrintSettingsFromPrefs already gets the few
+  // global defaults that we want, doesn't it?
+  InitPrintSettingsFromPrefs(*_retval, false, globalPrintSettings);
   return rv;
 }
 

widget/nsPrintSettingsService.cpp

@@ -938,10 +938,24 @@ nsPrintSettingsService::InitPrintSettingsFromPrefs(nsIPrintSettings* aPS,
 
   if (isInitialized) return NS_OK;
 
+  auto globalPrintSettings = aFlags;
+#ifndef MOZ_WIDGET_ANDROID
+  globalPrintSettings &= nsIPrintSettings::kInitSaveShrinkToFit |
+                         nsIPrintSettings::kInitSaveHeaderLeft |
+                         nsIPrintSettings::kInitSaveHeaderCenter |
+                         nsIPrintSettings::kInitSaveHeaderRight |
+                         nsIPrintSettings::kInitSaveFooterLeft |
+                         nsIPrintSettings::kInitSaveFooterCenter |
+                         nsIPrintSettings::kInitSaveFooterRight |
+                         nsIPrintSettings::kInitSaveEdges |
+                         nsIPrintSettings::kInitSaveReversed |
+                         nsIPrintSettings::kInitSaveInColor;
+#endif
+
   nsAutoString prtName;
   // read any non printer specific prefs
   // with empty printer name
-  nsresult rv = ReadPrefs(aPS, prtName, aFlags);
+  nsresult rv = ReadPrefs(aPS, prtName, globalPrintSettings);
   NS_ENSURE_SUCCESS(rv, rv);
 
   // Get the Printer Name from the PrintSettings to use as a prefix for Pref