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/Path_019.cpp b/docs/examples/Path_019.cpp
new file mode 100644
index 0000000..8972bb2
--- /dev/null
+++ b/docs/examples/Path_019.cpp
@@ -0,0 +1,20 @@
+// 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=875e32b4b1cb48d739325705fc0fa42c
+REG_FIDDLE(Path_019, 256, 256, true, 0) {
+void draw(SkCanvas* canvas) {
+    auto debugster = [](const char* prefix, const SkPath& path) -> void {
+        SkDebugf("%s path convexity is %s\n", prefix,
+                SkPath::kUnknown_Convexity == path.getConvexity() ? "unknown" :
+                SkPath::kConvex_Convexity == path.getConvexity() ? "convex" : "concave"); };
+        SkPoint quad[] = {{70, 70}, {20, 20}, {120, 20}, {120, 120}};
+        SkPath path;
+        path.addPoly(quad, SK_ARRAY_COUNT(quad), true);
+        debugster("initial", path);
+        path.setConvexity(SkPath::kConcave_Convexity);
+        debugster("after forcing concave", path);
+        path.setConvexity(SkPath::kUnknown_Convexity);
+        debugster("after forcing unknown", path);
+}
+}  // END FIDDLE