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>

1 files changed, 33 insertions, 0 deletions

diff --git a/docs/SkImage_Reference.bmh b/docs/SkImage_Reference.bmh
index 40146e8f14..4f2549b03a 100644
--- a/docs/SkImage_Reference.bmh
+++ b/docs/SkImage_Reference.bmh
@@ -1749,6 +1749,39 @@ Returns nullptr if Image contents are not encoded.
 #Line # rarely called management functions ##
 ##
 
+#Method const char* toString(SkString* string) const
+#In Utility
+#Line # converts Image to machine readable form ##
+Appends Image description to string, including unique ID, width, height, and
+whether the image is opaque.
+
+#Param string  storage for description; existing content is preserved ##
+
+#Return string appended with Image description ##
+
+#Example
+#Image 4
+    struct {
+        const char* name;
+        sk_sp<SkImage> image;
+    } tests[] = { { "image", image }, { "bitmap", SkImage::MakeFromBitmap(source) },
+          { "texture", SkImage::MakeFromTexture(canvas->getGrContext(), backEndTexture,
+                            kTopLeft_GrSurfaceOrigin, kN32_SkColorType, kOpaque_SkAlphaType,
+                            nullptr) } };
+    SkString string;
+    SkPaint paint;
+    for (const auto& test : tests ) {
+        string.printf("%s: ", test.name);
+        test.image ? (void) test.image->toString(&string) : string.append("no image");
+        canvas->drawString(string, 10, 20, paint);
+        canvas->translate(0, 20);
+    }
+##
+
+#SeeAlso SkPaint::toString
+
+#Method ##
+
 # ------------------------------------------------------------------------------
 
 #Method sk_sp<SkImage> makeSubset(const SkIRect& subset) const