Bug 1563996 - Make browser.xul.error_pages.enabled a static pref. r=bzbarsky

Differential Revision: https://phabricator.services.mozilla.com/D37201

--HG--
extra : moz-landing-system : lando

browser/app/profile/firefox.js

@@ -665,7 +665,6 @@ pref("mousewheel.with_meta.action", 1); // win key on Win, Super/Hyper on Linux
 pref("mousewheel.with_control.action",3);
 pref("mousewheel.with_win.action", 1);
 
-pref("browser.xul.error_pages.enabled", true);
 pref("browser.xul.error_pages.expert_bad_cert", false);
 pref("browser.xul.error_pages.show_safe_browsing_details_on_load", false);
 

docshell/base/nsDocShell.cpp

@@ -243,10 +243,6 @@ using namespace mozilla::net;
 
 static NS_DEFINE_CID(kAppShellCID, NS_APPSHELL_CID);
 
-// True means sUseErrorPages has been added to
-// preferences var cache.
-static bool gAddedPreferencesVarCache = false;
-
 // Number of documents currently loading
 static int32_t gNumberOfDocumentsLoading = 0;
 
@@ -271,8 +267,6 @@ const char kBrandBundleURL[] = "chrome://branding/locale/brand.properties";
 const char kAppstringsBundleURL[] =
     "chrome://global/locale/appstrings.properties";
 
-bool nsDocShell::sUseErrorPages = false;
-
 // Global reference to the URI fixup service.
 nsIURIFixup* nsDocShell::sURIFixup = nullptr;
 
@@ -2088,7 +2082,8 @@ nsDocShell::GetUseErrorPages(bool* aUseErrorPages) {
 
 NS_IMETHODIMP
 nsDocShell::SetUseErrorPages(bool aUseErrorPages) {
-  // If mUseErrorPages is set explicitly, stop using sUseErrorPages.
+  // If mUseErrorPages is set explicitly, stop using the
+  // browser.xul.error_pages_enabled pref.
   if (mObserveErrorPages) {
     mObserveErrorPages = false;
   }
@@ -4949,14 +4944,7 @@ nsDocShell::Create() {
       "security.strict_security_checks.enabled", mUseStrictSecurityChecks);
 
   // Should we use XUL error pages instead of alerts if possible?
-  mUseErrorPages =
-      Preferences::GetBool("browser.xul.error_pages.enabled", mUseErrorPages);
-
-  if (!gAddedPreferencesVarCache) {
-    Preferences::AddBoolVarCache(
-        &sUseErrorPages, "browser.xul.error_pages.enabled", mUseErrorPages);
-    gAddedPreferencesVarCache = true;
-  }
+  mUseErrorPages = StaticPrefs::browser_xul_error_pages_enabled();
 
   mDisableMetaRefreshWhenInactive =
       Preferences::GetBool("browser.meta_refresh_when_inactive.disabled",

docshell/base/nsDocShell.h

@@ -12,6 +12,7 @@
 #include "mozilla/LinkedList.h"
 #include "mozilla/Maybe.h"
 #include "mozilla/Move.h"
+#include "mozilla/StaticPrefs.h"
 #include "mozilla/TimeStamp.h"
 #include "mozilla/UniquePtr.h"
 #include "mozilla/WeakPtr.h"
@@ -944,7 +945,9 @@ class nsDocShell final : public nsDocLoader,
   already_AddRefed<mozilla::dom::ChildSHistory> GetRootSessionHistory();
 
   inline bool UseErrorPages() {
-    return (mObserveErrorPages ? sUseErrorPages : mUseErrorPages);
+    return (mObserveErrorPages
+                ? mozilla::StaticPrefs::browser_xul_error_pages_enabled()
+                : mUseErrorPages);
   }
 
   bool CSSErrorReportingEnabled() const { return mCSSErrorReportingEnabled; }
@@ -984,9 +987,6 @@ class nsDocShell final : public nsDocLoader,
  private:  // data members
   static nsIURIFixup* sURIFixup;
 
-  // Cached value of the "browser.xul.error_pages.enabled" preference.
-  static bool sUseErrorPages;
-
 #ifdef DEBUG
   // We're counting the number of |nsDocShells| to help find leaks
   static unsigned long gNumberOfDocShells;

mobile/android/app/mobile.js

@@ -277,9 +277,6 @@ pref("chrome.override_package.global", "browser");
 pref("chrome.override_package.mozapps", "browser");
 pref("chrome.override_package.passwordmgr", "browser");
 
-// enable xul error pages
-pref("browser.xul.error_pages.enabled", true);
-
 // disable color management
 pref("gfx.color_management.mode", 0);
 

modules/libpref/init/StaticPrefList.h

@@ -975,6 +975,14 @@ VARCACHE_PREF(
 
 PREF("browser.visited_color", String, "")
 
+// Enable xul error pages.
+VARCACHE_PREF(
+  Live,
+  "browser.xul.error_pages.enabled",
+   browser_xul_error_pages_enabled,
+  bool, true
+)
+
 //---------------------------------------------------------------------------
 // Prefs starting with "canvas."
 //---------------------------------------------------------------------------