Auto merge of #13911 - upsuper:bug1312338, r=Manishearth

Use nsACString to pass string params for bindings

This is the Servo side change of [bug 1312338](https://bugzilla.mozilla.org/show_bug.cgi?id=1312338) which has been reviewed by @Manishearth.

r? @Manishearth

(This should not be merged before the Gecko side code lands in m-c)

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components/style/binding_tools/regen.py

@@ -233,7 +233,13 @@ COMPILATION_TARGETS = {
     # Generation of the ffi bindings.
     "bindings": {
         "target_dir": "../gecko_bindings",
-        "raw_lines": [],
+        "blacklist_types": [
+            "nsACString_internal",
+        ],
+        "raw_lines": [
+            "pub use nsstring::nsACString;",
+            "type nsACString_internal = nsACString;",
+        ],
         "flags": [
             "--ignore-methods",
         ],

components/style/gecko_bindings/bindings.rs

@@ -1,5 +1,7 @@
 /* automatically generated by rust-bindgen */
 
+pub use nsstring::nsACString;
+type nsACString_internal = nsACString;
 pub type ServoComputedValuesStrong = ::gecko_bindings::sugar::ownership::Strong<ServoComputedValues>;
 pub type ServoComputedValuesBorrowedOrNull<'a> = Option<&'a ServoComputedValues>;
 pub type ServoComputedValuesBorrowed<'a> = &'a ServoComputedValues;
@@ -837,10 +839,10 @@ extern "C" {
     pub fn Servo_Node_ClearNodeData(node: RawGeckoNodeBorrowed);
 }
 extern "C" {
-    pub fn Servo_StyleSheet_FromUTF8Bytes(bytes: *const u8, length: u32,
+    pub fn Servo_StyleSheet_FromUTF8Bytes(data: *const nsACString_internal,
                                           parsing_mode: SheetParsingMode,
-                                          base_bytes: *const u8,
-                                          base_length: u32,
+                                          base_url:
+                                              *const nsACString_internal,
                                           base: *mut ThreadSafeURIHolder,
                                           referrer: *mut ThreadSafeURIHolder,
                                           principal:
@@ -876,10 +878,9 @@ extern "C" {
                                                      RawServoStyleSheetBorrowed);
 }
 extern "C" {
-    pub fn Servo_ParseProperty(property_bytes: *const u8,
-                               property_length: u32, value_bytes: *const u8,
-                               value_length: u32, base_bytes: *const u8,
-                               base_length: u32,
+    pub fn Servo_ParseProperty(property: *const nsACString_internal,
+                               value: *const nsACString_internal,
+                               base_url: *const nsACString_internal,
                                base: *mut ThreadSafeURIHolder,
                                referrer: *mut ThreadSafeURIHolder,
                                principal: *mut ThreadSafePrincipalHolder)
@@ -893,7 +894,7 @@ extern "C" {
      -> ServoComputedValuesStrong;
 }
 extern "C" {
-    pub fn Servo_ParseStyleAttribute(bytes: *const u8, length: u32)
+    pub fn Servo_ParseStyleAttribute(data: *const nsACString_internal)
      -> RawServoDeclarationBlockStrong;
 }
 extern "C" {
@@ -907,8 +908,8 @@ extern "C" {
                                                     buffer: *mut nsString);
 }
 extern "C" {
-    pub fn Servo_CSSSupports(name: *const u8, name_length: u32,
-                             value: *const u8, value_length: u32) -> bool;
+    pub fn Servo_CSSSupports(name: *const nsACString_internal,
+                             value: *const nsACString_internal) -> bool;
 }
 extern "C" {
     pub fn Servo_ComputedValues_Get(node: RawGeckoNodeBorrowed)

components/style/gecko_bindings/nsstring_vendor/src/lib.rs

@@ -144,6 +144,7 @@ use std::ptr;
 use std::mem;
 use std::fmt;
 use std::cmp;
+use std::str;
 use std::u32;
 
 //////////////////////////////////
@@ -569,6 +570,10 @@ impl nsACString {
             Gecko_AppendUTF16toCString(self as *mut _, other as *const _);
         }
     }
+
+    pub unsafe fn as_str_unchecked(&self) -> &str {
+        str::from_utf8_unchecked(self)
+    }
 }
 
 impl<'a> From<&'a str> for nsCString<'a> {