Return const SVGViewSpec* from SVGViewSpec::Create*

The returned object shouldn't be mutable (and cannot be mutated).

Change-Id: I2213472fe99fb64acc95bf8e3e45307bc895b0ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2517727
Commit-Queue: Stephen Chenney <schenney@chromium.org>
Auto-Submit: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824103}

third_party/blink/renderer/core/svg/svg_svg_element.cc

@@ -689,7 +689,7 @@ void SVGSVGElement::SetViewSpec(const SVGViewSpec* view_spec) {
 void SVGSVGElement::SetupInitialView(const String& fragment_identifier,
                                      Element* anchor_node) {
   if (fragment_identifier.StartsWith("svgView(")) {
-    SVGViewSpec* view_spec =
+    const SVGViewSpec* view_spec =
         SVGViewSpec::CreateFromFragment(fragment_identifier);
     if (view_spec) {
       UseCounter::Count(GetDocument(),
@@ -704,7 +704,7 @@ void SVGSVGElement::SetupInitialView(const String& fragment_identifier,
     // displayed in the SVG viewport. Any view specification attributes included
     // on the given 'view' element override the corresponding view specification
     // attributes on the root 'svg' element.
-    SVGViewSpec* view_spec =
+    const SVGViewSpec* view_spec =
         SVGViewSpec::CreateForViewElement(*svg_view_element);
     UseCounter::Count(GetDocument(),
                       WebFeature::kSVGSVGElementFragmentSVGViewElement);

third_party/blink/renderer/core/svg/svg_view_spec.cc

@@ -40,14 +40,15 @@ void SVGViewSpec::Trace(Visitor* visitor) const {
   visitor->Trace(transform_);
 }
 
-SVGViewSpec* SVGViewSpec::CreateFromFragment(const String& fragment) {
+const SVGViewSpec* SVGViewSpec::CreateFromFragment(const String& fragment) {
   SVGViewSpec* view_spec = MakeGarbageCollected<SVGViewSpec>();
   if (!view_spec->ParseViewSpec(fragment))
     return nullptr;
   return view_spec;
 }
 
-SVGViewSpec* SVGViewSpec::CreateForViewElement(const SVGViewElement& view) {
+const SVGViewSpec* SVGViewSpec::CreateForViewElement(
+    const SVGViewElement& view) {
   SVGViewSpec* view_spec = MakeGarbageCollected<SVGViewSpec>();
   if (view.viewBox()->CurrentValue()->IsValid())
     view_spec->view_box_ = view.viewBox()->CurrentValue()->Clone();

third_party/blink/renderer/core/svg/svg_view_spec.h

@@ -32,8 +32,8 @@ class SVGViewElement;
 
 class SVGViewSpec final : public GarbageCollected<SVGViewSpec> {
  public:
-  static SVGViewSpec* CreateFromFragment(const String&);
-  static SVGViewSpec* CreateForViewElement(const SVGViewElement&);
+  static const SVGViewSpec* CreateFromFragment(const String&);
+  static const SVGViewSpec* CreateForViewElement(const SVGViewElement&);
 
   SVGViewSpec();