Revert "Reland "remove toString""

This reverts commit 92e37b6d79f12ccfaaf7671413316952d182267d.

Reason for revert: toString still used by flutter

Original change's description:
> Reland "remove toString"
> 
> This reverts commit 32a4910e57b1fdd3c8671de1ee85e05ca21d079f.
> 
> Reason for revert: SkMatrix::toString use has been removed from flutter and has been picked up in fuchsia
> 
> Original change's description:
> > 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>
> 
> TBR=bsalomon@google.com,brianosman@google.com,caryclark@google.com,caryclark@skia.org
> 
> # Not skipping CQ checks because original CL landed > 1 day ago.
> 
> Bug: 830651
> Change-Id: Ida8725b6051132d8c46faf99358a8fcc1bcabf34
> Reviewed-on: https://skia-review.googlesource.com/129623
> Reviewed-by: Cary Clark <caryclark@skia.org>
> Reviewed-by: Cary Clark <caryclark@google.com>
> Commit-Queue: Cary Clark <caryclark@google.com>

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

Change-Id: Iafc59ffc1b3db67c520ba31bf12d68e1b46c0ea2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 830651
Reviewed-on: https://skia-review.googlesource.com/131082
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Cary Clark <caryclark@google.com>
diff --git a/docs/SkMatrix_Reference.bmh b/docs/SkMatrix_Reference.bmh
index 1211588..4ab498a 100644
--- a/docs/SkMatrix_Reference.bmh
+++ b/docs/SkMatrix_Reference.bmh
@@ -4103,7 +4103,40 @@
 ##
 ##
 
-#SeeAlso SkPath::dump
+#SeeAlso toString
+
+##
+
+# ------------------------------------------------------------------------------
+
+#Method void toString(SkString* str) const
+#In Utility
+#Line # converts Matrix to machine readable form ##
+Creates string representation of Matrix. Floating point values
+are written with limited precision; it may not be possible to reconstruct
+original Matrix from output.
+
+#Param str  storage for string representation of Matrix ##
+
+#Example
+    SkMatrix matrix;
+    matrix.setRotate(45);
+    SkString mStr, neStr;
+    matrix.toString(&mStr);
+    SkMatrix nearlyEqual;
+    nearlyEqual.setAll(0.7071f, -0.7071f, 0,   0.7071f, 0.7071f, 0,   0, 0, 1);
+    nearlyEqual.toString(&neStr);
+    SkDebugf("mStr  %s\n", mStr.c_str());
+    SkDebugf("neStr %s\n", neStr.c_str());
+    SkDebugf("matrix %c= nearlyEqual\n", matrix == nearlyEqual ? '=' : '!');
+#StdOut
+mStr  [  0.7071  -0.7071   0.0000][  0.7071   0.7071   0.0000][  0.0000   0.0000   1.0000]
+neStr [  0.7071  -0.7071   0.0000][  0.7071   0.7071   0.0000][  0.0000   0.0000   1.0000]
+matrix != nearlyEqual
+##
+##
+
+#SeeAlso dump
 
 ##