Replace filter outsets with bounds mapping in Blink.

third_party/WebKit/Source/platform/graphics/filters/FilterOperation.h

Index: third_party/WebKit/Source/platform/graphics/filters/FilterOperation.h
diff --git a/third_party/WebKit/Source/platform/graphics/filters/FilterOperation.h b/third_party/WebKit/Source/platform/graphics/filters/FilterOperation.h
index 7a9cdffb2a7af4d83044ff06b50dde28e8c6db71..cb429d2ed765cfc7aa5190b7228f158836ba38e6 100644
--- a/third_party/WebKit/Source/platform/graphics/filters/FilterOperation.h
+++ b/third_party/WebKit/Source/platform/graphics/filters/FilterOperation.h
@@ -100,6 +100,12 @@ public:
     // True if the the value of one pixel can affect the value of another pixel under this operation, such as blur.
     virtual bool movesPixels() const { return false; }
 
+    // Can map "forward" to determine which pixels in a destination rect are
+    // affected by pixels in the source rect, or "backward" to determine which
+    // pixels in the source rect are required for a destination rect.
+    // See also FilterEffect::mapRect.
+    virtual FloatRect mapRect(const FloatRect& rect, bool forward) const { return rect; }
+
 protected:
     FilterOperation(OperationType type)
         : m_type(type)
@@ -124,6 +130,7 @@ public:
 
     bool affectsOpacity() const override { return true; }
     bool movesPixels() const override { return true; }
+    FloatRect mapRect(const FloatRect&, bool forward) const override;
 
     const String& url() const { return m_url; }
     const AtomicString& fragment() const { return m_fragment; }
@@ -252,7 +259,7 @@ public:
 
     bool affectsOpacity() const override { return true; }
     bool movesPixels() const override { return true; }
-
+    FloatRect mapRect(const FloatRect&, bool forward) const override;
 
 private:
     FilterOperation* blend(const FilterOperation* from, double progress) const override;
@@ -290,7 +297,7 @@ public:
 
     bool affectsOpacity() const override { return true; }
     bool movesPixels() const override { return true; }
-
+    FloatRect mapRect(const FloatRect&, bool forward) const override;
 
 private:
     FilterOperation* blend(const FilterOperation* from, double progress) const override;
@@ -329,6 +336,7 @@ public:
 
     bool affectsOpacity() const override { return true; }
     bool movesPixels() const override { return true; }
+    FloatRect mapRect(const FloatRect&, bool forward) const override;
 
 private:
     FilterOperation* blend(const FilterOperation* from, double progress) const override;