Bug 977757 - 2/3 - add nsCSSProps::eEnabledInChromeOrCertifiedApp bit, and use it for will-change - r=dbaron,bz

layout/style/nsCSSParser.cpp

@@ -45,6 +45,7 @@
 #include "mozilla/Preferences.h"
 #include "nsRuleData.h"
 #include "mozilla/CSSVariableValues.h"
+#include "mozilla/dom/URL.h"
 
 using namespace mozilla;
 
@@ -255,6 +256,9 @@ public:
     if (mUnsafeRulesEnabled) {
       enabledState |= nsCSSProps::eEnabledInUASheets;
     }
+    if (mIsChromeOrCertifiedApp) {
+      enabledState |= nsCSSProps::eEnabledInChromeOrCertifiedApp;
+    }
     return nsCSSProps::LookupProperty(aProperty, enabledState);
   }
 
@@ -884,6 +888,12 @@ protected:
   // True if unsafe rules should be allowed
   bool mUnsafeRulesEnabled : 1;
 
+  // True if we are in parsing rules for Chrome or Certified App content,
+  // in which case CSS properties with the
+  // CSS_PROPERTY_ALWAYS_ENABLED_IN_CHROME_OR_CERTIFIED_APP
+  // flag should be allowed.
+  bool mIsChromeOrCertifiedApp : 1;
+
   // True if viewport units should be allowed.
   bool mViewportUnitsEnabled : 1;
 
@@ -978,6 +988,7 @@ CSSParserImpl::CSSParserImpl()
     mHashlessColorQuirk(false),
     mUnitlessLengthQuirk(false),
     mUnsafeRulesEnabled(false),
+    mIsChromeOrCertifiedApp(false),
     mViewportUnitsEnabled(true),
     mHTMLMediaMode(false),
     mParsingCompoundProperty(false),
@@ -1118,6 +1129,9 @@ CSSParserImpl::ParseSheet(const nsAString& aInput,
   }
 
   mUnsafeRulesEnabled = aAllowUnsafeRules;
+  mIsChromeOrCertifiedApp =
+    dom::IsChromeURI(aSheetURI) ||
+    aSheetPrincipal->GetAppStatus() == nsIPrincipal::APP_STATUS_CERTIFIED;
 
   nsCSSToken* tk = &mToken;
   for (;;) {
@@ -1141,6 +1155,7 @@ CSSParserImpl::ParseSheet(const nsAString& aInput,
   ReleaseScanner();
 
   mUnsafeRulesEnabled = false;
+  mIsChromeOrCertifiedApp = false;
 
   // XXX check for low level errors
   return NS_OK;

layout/style/nsCSSPropList.h

@@ -3791,7 +3791,8 @@ CSS_PROP_DISPLAY(
     will_change,
     WillChange,
     CSS_PROPERTY_PARSE_FUNCTION |
-        CSS_PROPERTY_VALUE_LIST_USES_COMMAS,
+        CSS_PROPERTY_VALUE_LIST_USES_COMMAS |
+        CSS_PROPERTY_ALWAYS_ENABLED_IN_CHROME_OR_CERTIFIED_APP,
     "layout.css.will-change.enabled",
     0,
     nullptr,

layout/style/nsCSSProps.cpp

@@ -395,7 +395,7 @@ nsCSSProps::LookupProperty(const nsACString& aProperty,
   }
   MOZ_ASSERT(eCSSAliasCount != 0,
              "'res' must be an alias at this point so we better have some!");
-  // We intentionally don't support eEnabledInUASheets
+  // We intentionally don't support eEnabledInUASheets or eEnabledInChromeOrCertifiedApp
   // for aliases yet because it's unlikely there will be a need for it.
   if (IsEnabled(res) || aEnabled == eIgnoreEnabledState) {
     res = gAliases[res - eCSSProperty_COUNT];

layout/style/nsCSSProps.h

@@ -201,6 +201,14 @@ static_assert((CSS_PROPERTY_PARSE_PROPERTY_MASK &
 // In other words, this bit has no effect on the use of aliases.
 #define CSS_PROPERTY_ALWAYS_ENABLED_IN_UA_SHEETS  (1<<22)
 
+// This property is always enabled in chrome and in certified apps. This is
+// meant to be used together with a pref that enables the property for
+// non-privileged content. Note that if such a property has an alias, then any
+// use of that alias in privileged content will still be ignored unless the
+// pref is enabled. In other words, this bit has no effect on the use of
+// aliases.
+#define CSS_PROPERTY_ALWAYS_ENABLED_IN_CHROME_OR_CERTIFIED_APP (1<<23)
+
 /**
  * Types of animatable values.
  */
@@ -264,6 +272,8 @@ public:
     eEnabledForAllContent = 0,
     // Enable a property in UA sheets.
     eEnabledInUASheets    = 0x01,
+    // Enable a property in privileged content, i.e. chrome or Certified Apps
+    eEnabledInChromeOrCertifiedApp = 0x02,
     // Special value to unconditionally enable a property. This implies all the
     // bits above, but is strictly more than just their OR-ed union.
     // This just skips any test so a property will be enabled even if it would
@@ -467,6 +477,11 @@ public:
     {
       return true;
     }
+    if ((aEnabled & eEnabledInChromeOrCertifiedApp) &&
+        PropHasFlags(aProperty, CSS_PROPERTY_ALWAYS_ENABLED_IN_CHROME_OR_CERTIFIED_APP))
+    {
+      return true;
+    }
     return false;
   }