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/Matrix_077.cpp b/docs/examples/Matrix_077.cpp
new file mode 100644
index 0000000..95319cc
--- /dev/null
+++ b/docs/examples/Matrix_077.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=f99dcb00296d0c56b6c0e178e94b3534
+REG_FIDDLE(Matrix_077, 256, 256, false, 0) {
+void draw(SkCanvas* canvas) {
+    SkMatrix matrix;
+    matrix.reset();
+    const int count = 4;
+    SkPoint src[count];
+    matrix.mapRectToQuad(src, {40, 70, 180, 220} );
+    SkPaint paint;
+    paint.setARGB(77, 23, 99, 154);
+    for (int i = 0; i < 5; ++i) {
+        SkPoint dst[count];
+        matrix.mapPoints(dst, src, count);
+        canvas->drawPoints(SkCanvas::kPolygon_PointMode, count, dst, paint);
+        matrix.preRotate(35, 128, 128);
+    }
+}
+}  // END FIDDLE