Revert "remove toString"

This reverts commit 5191880cbf3ee4d122b0d11b4945fbab0784fda7.

Reason for revert: broke flutter

Original change's description:
> remove toString
> 
> toString may have been used by obsolete debugger only
> find out if that is so
> 
> R=​brianosman@google.com,bsalomon@google.com
> 
> Docs-Preview: https://skia.org/?cl=119894
> Bug:830651
> Change-Id: I737f19b7d3fbc869bea2f443fa3b5ed7c1393ffd
> Reviewed-on: https://skia-review.googlesource.com/119894
> Commit-Queue: Cary Clark <caryclark@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>

TBR=bsalomon@google.com,brianosman@google.com,caryclark@google.com,caryclark@skia.org

Change-Id: I9f81de6c3615ee0608bcea9081b77239b4b8816c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 830651
Reviewed-on: https://skia-review.googlesource.com/129340
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Cary Clark <caryclark@google.com>
diff --git a/src/effects/Sk2DPathEffect.cpp b/src/effects/Sk2DPathEffect.cpp
index 6c2c4c2..a541b91 100644
--- a/src/effects/Sk2DPathEffect.cpp
+++ b/src/effects/Sk2DPathEffect.cpp
@@ -74,6 +74,13 @@
     buffer.writeMatrix(fMatrix);
 }
 
+void Sk2DPathEffect::toString(SkString* str) const {
+    str->appendf("(matrix: %.2f %.2f %.2f %.2f %.2f %.2f %.2f %.2f %.2f)",
+            fMatrix[SkMatrix::kMScaleX], fMatrix[SkMatrix::kMSkewX],  fMatrix[SkMatrix::kMTransX],
+            fMatrix[SkMatrix::kMSkewY],  fMatrix[SkMatrix::kMScaleY], fMatrix[SkMatrix::kMTransY],
+            fMatrix[SkMatrix::kMPersp0], fMatrix[SkMatrix::kMPersp1], fMatrix[SkMatrix::kMPersp2]);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 bool SkLine2DPathEffect::filterPath(SkPath* dst, const SkPath& src,
@@ -110,6 +117,14 @@
     buffer.writeScalar(fWidth);
 }
 
+
+void SkLine2DPathEffect::toString(SkString* str) const {
+    str->appendf("SkLine2DPathEffect: (");
+    this->INHERITED::toString(str);
+    str->appendf("width: %f", fWidth);
+    str->appendf(")");
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 SkPath2DPathEffect::SkPath2DPathEffect(const SkMatrix& m, const SkPath& p)
@@ -133,3 +148,11 @@
                               SkPath* dst) const {
     dst->addPath(fPath, loc.fX, loc.fY);
 }
+
+void SkPath2DPathEffect::toString(SkString* str) const {
+    str->appendf("SkPath2DPathEffect: (");
+    this->INHERITED::toString(str);
+    // TODO: print out path information
+    str->appendf(")");
+}
+