Auto merge of #18310 - nnethercote:bug-1394729, r=heycam

Measure memory usage of Stylo's Rule Tree.

<!-- Please describe your changes on the following line: -->
This is for https://bugzilla.mozilla.org/show_bug.cgi?id=1394729, which was r=heycam.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because tests exist in Gecko.

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components/style/gecko/generated/bindings.rs

@@ -61,6 +61,7 @@ use gecko_bindings::structs::SeenPtrs;
 use gecko_bindings::structs::ServoBundledURI;
 use gecko_bindings::structs::ServoElementSnapshot;
 use gecko_bindings::structs::ServoElementSnapshotTable;
+use gecko_bindings::structs::ServoStyleSetSizes;
 use gecko_bindings::structs::SheetParsingMode;
 use gecko_bindings::structs::StyleBasicShape;
 use gecko_bindings::structs::StyleBasicShapeType;
@@ -2067,6 +2068,11 @@ extern "C" {
                                                      RawServoDeclarationBlockBorrowed)
      -> ServoStyleContextStrong;
 }
+extern "C" {
+    pub fn Servo_StyleSet_AddSizeOfExcludingThis(malloc_size_of: MallocSizeOf,
+                                                 sizes: *mut ServoStyleSetSizes,
+                                                 set: RawServoStyleSetBorrowed);
+}
 extern "C" {
     pub fn Servo_StyleContext_AddRef(ctx: ServoStyleContextBorrowed);
 }

components/style/gecko/generated/structs_debug.rs

@@ -5456,6 +5456,38 @@ pub mod root {
                         "Alignment of field: " , stringify ! ( GeckoEffects )
                         , "::" , stringify ! ( gecko ) ));
         }
+        #[repr(C)]
+        #[derive(Debug, Copy)]
+        pub struct ServoStyleSetSizes {
+            pub mStylistRuleTree: usize,
+            pub mOther: usize,
+        }
+        #[test]
+        fn bindgen_test_layout_ServoStyleSetSizes() {
+            assert_eq!(::std::mem::size_of::<ServoStyleSetSizes>() , 16usize ,
+                       concat ! (
+                       "Size of: " , stringify ! ( ServoStyleSetSizes ) ));
+            assert_eq! (::std::mem::align_of::<ServoStyleSetSizes>() , 8usize
+                        , concat ! (
+                        "Alignment of " , stringify ! ( ServoStyleSetSizes )
+                        ));
+            assert_eq! (unsafe {
+                        & ( * ( 0 as * const ServoStyleSetSizes ) ) .
+                        mStylistRuleTree as * const _ as usize } , 0usize ,
+                        concat ! (
+                        "Alignment of field: " , stringify ! (
+                        ServoStyleSetSizes ) , "::" , stringify ! (
+                        mStylistRuleTree ) ));
+            assert_eq! (unsafe {
+                        & ( * ( 0 as * const ServoStyleSetSizes ) ) . mOther
+                        as * const _ as usize } , 8usize , concat ! (
+                        "Alignment of field: " , stringify ! (
+                        ServoStyleSetSizes ) , "::" , stringify ! ( mOther )
+                        ));
+        }
+        impl Clone for ServoStyleSetSizes {
+            fn clone(&self) -> Self { *self }
+        }
         #[repr(u8)]
         /// Enumeration that represents one of the two supported style system backends.
         #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]

components/style/gecko/generated/structs_release.rs

@@ -5344,6 +5344,38 @@ pub mod root {
                         "Alignment of field: " , stringify ! ( GeckoEffects )
                         , "::" , stringify ! ( gecko ) ));
         }
+        #[repr(C)]
+        #[derive(Debug, Copy)]
+        pub struct ServoStyleSetSizes {
+            pub mStylistRuleTree: usize,
+            pub mOther: usize,
+        }
+        #[test]
+        fn bindgen_test_layout_ServoStyleSetSizes() {
+            assert_eq!(::std::mem::size_of::<ServoStyleSetSizes>() , 16usize ,
+                       concat ! (
+                       "Size of: " , stringify ! ( ServoStyleSetSizes ) ));
+            assert_eq! (::std::mem::align_of::<ServoStyleSetSizes>() , 8usize
+                        , concat ! (
+                        "Alignment of " , stringify ! ( ServoStyleSetSizes )
+                        ));
+            assert_eq! (unsafe {
+                        & ( * ( 0 as * const ServoStyleSetSizes ) ) .
+                        mStylistRuleTree as * const _ as usize } , 0usize ,
+                        concat ! (
+                        "Alignment of field: " , stringify ! (
+                        ServoStyleSetSizes ) , "::" , stringify ! (
+                        mStylistRuleTree ) ));
+            assert_eq! (unsafe {
+                        & ( * ( 0 as * const ServoStyleSetSizes ) ) . mOther
+                        as * const _ as usize } , 8usize , concat ! (
+                        "Alignment of field: " , stringify ! (
+                        ServoStyleSetSizes ) , "::" , stringify ! ( mOther )
+                        ));
+        }
+        impl Clone for ServoStyleSetSizes {
+            fn clone(&self) -> Self { *self }
+        }
         #[repr(u8)]
         /// Enumeration that represents one of the two supported style system backends.
         #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]