Compile all fiddle examples locally

Motivation: it would be a good idea if the API documentation examples
were checked into the skia repository, so we could make sure they
compile as part of the commit queue.

Fiddle would make/update a named fiddle each time it gets a new
commit of Skia, extracted from the code in the examples/ directory.
The docs would point at those named fiddles.  Named fiddles have urls
in the form:

    https://fiddle.skia.org/c/@Bitmap_000

Then we would stick a link to the example into the header documentation
like this:

    /** Allocates the pixel memory for the bitmap, given its dimensions
        and SkColorType. Returns true on success, where success means
        either setPixels() or setPixelRef() was called.

        @param bitmap  SkBitmap containing SkImageInfo as input, and
                       SkPixelRef as output
        @return        true if SkPixelRef was allocated

        @example       https://fiddle.skia.org/c/@Bitmap_000
    */
    bool allocPixelRef(SkBitmap* bitmap) override;

There are still around 200 disabled examples that need to be fixed
(these result from API changes since the author left).

Change-Id: I14a31348a9ccaaa31f65424b91e3a3533d2583a7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/198824
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
diff --git a/docs/examples/Canvas_121.cpp b/docs/examples/Canvas_121.cpp
new file mode 100644
index 0000000..673ad1b
--- /dev/null
+++ b/docs/examples/Canvas_121.cpp
@@ -0,0 +1,21 @@
+// Copyright 2019 Google LLC.
+// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
+#include "fiddle/examples.h"
+// HASH=3412c2a16cb529af0e04878d264451f2
+REG_FIDDLE(Canvas_121, 256, 256, false, 6) {
+void draw(SkCanvas* canvas) {
+    // SkBitmap source = checkerboard;
+    SkPaint paint;
+    paint.setFilterQuality(kLow_SkFilterQuality);
+    paint.setAntiAlias(true);
+    SkPoint cubics[] = { { 3, 1 },    { 4, 2 }, { 5, 1 },    { 7, 3 },
+                      /* { 7, 3 }, */ { 6, 4 }, { 7, 5 },    { 5, 7 },
+                      /* { 5, 7 }, */ { 4, 6 }, { 3, 7 },    { 1, 5 },
+                      /* { 1, 5 }, */ { 2, 4 }, { 1, 3 }, /* { 3, 1 } */ };
+    SkPoint texCoords[] = { { 0, 0 }, { 0, 62}, { 62, 62}, { 62, 0 } };
+    paint.setShader(SkShader::MakeBitmapShader(source, SkShader::kClamp_TileMode,
+                                                       SkShader::kClamp_TileMode, nullptr));
+    canvas->scale(30, 30);
+    canvas->drawPatch(cubics, nullptr, texCoords, paint);
+}
+}  // END FIDDLE