Have SVGAnimatedPropertyCommon::current_value_ always be set

Rather than having |current_value_| be null when an animation is not
active, have it point to the same value as |base_value_|. This avoids
having to null-check |current_value_| for each access (in CurrentValue).

Bug: 1017723
Change-Id: I39c56ec30ee9c92692db4f68be49a8094bf012b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1932542Reviewed-by: Stephen Chenney <schenney@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#719070}

third_party/blink/renderer/core/svg/properties/svg_animated_property.h

@@ -119,10 +119,7 @@ template <typename Property>
 class SVGAnimatedPropertyCommon : public SVGAnimatedPropertyBase {
  public:
   Property* BaseValue() { return base_value_.Get(); }
-
-  Property* CurrentValue() {
-    return current_value_ ? current_value_.Get() : base_value_.Get();
-  }
+  Property* CurrentValue() { return current_value_.Get(); }
 
   const Property* CurrentValue() const {
     return const_cast<SVGAnimatedPropertyCommon*>(this)->CurrentValue();
@@ -132,7 +129,7 @@ class SVGAnimatedPropertyCommon : public SVGAnimatedPropertyBase {
 
   const SVGPropertyBase& BaseValueBase() const override { return *base_value_; }
 
-  bool IsAnimating() const override { return current_value_; }
+  bool IsAnimating() const override { return current_value_ != base_value_; }
 
   SVGParsingError AttributeChanged(const String& value) override {
     static_assert(Property::kInitialValueBits <= kInitialValueStorageBits,
@@ -160,8 +157,7 @@ class SVGAnimatedPropertyCommon : public SVGAnimatedPropertyBase {
   }
 
   void AnimationEnded() override {
-    current_value_.Clear();
-
+    current_value_ = base_value_;
     SVGAnimatedPropertyBase::AnimationEnded();
   }
 
@@ -183,7 +179,8 @@ class SVGAnimatedPropertyCommon : public SVGAnimatedPropertyBase {
                                 attribute_name,
                                 css_property_id,
                                 initial_value_bits),
-        base_value_(initial_value) {}
+        base_value_(initial_value),
+        current_value_(initial_value) {}
 
  private:
   Member<Property> base_value_;
@@ -201,7 +198,7 @@ class SVGAnimatedProperty : public SVGAnimatedPropertyCommon<Property> {
   // SVGAnimated* DOM Spec implementations:
 
   // baseVal()/setBaseVal()/animVal() are only to be used from SVG DOM
-  // implementation.  Use currentValue() from C++ code.
+  // implementation.  Use CurrentValue() from C++ code.
   PrimitiveType baseVal() { return this->BaseValue()->Value(); }
 
   void setBaseVal(PrimitiveType value, ExceptionState&) {
@@ -288,11 +285,12 @@ class SVGAnimatedProperty<Property, TearOffType, void>
       anim_val_tear_off_->SetTarget(this->CurrentValue());
   }
 
-  // When still (not animated):
-  //     Both m_animValTearOff and m_baseValTearOff target m_baseValue.
+  // When not animated:
+  //     Both |anim_val_tear_off_| and |base_val_tear_off_| target
+  //     |base_value_|.
   // When animated:
-  //     m_animValTearOff targets m_currentValue.
-  //     m_baseValTearOff targets m_baseValue.
+  //     |anim_val_tear_off_| targets |current_value_|.
+  //     |base_val_tear_off_| targets |base_value_|.
   Member<TearOffType> base_val_tear_off_;
   Member<TearOffType> anim_val_tear_off_;
 };