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_051.cpp b/docs/examples/Canvas_051.cpp
new file mode 100644
index 0000000..5976312
--- /dev/null
+++ b/docs/examples/Canvas_051.cpp
@@ -0,0 +1,24 @@
+// 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=1d4e0632c97e42692775d834fe10aa99
+REG_FIDDLE(Canvas_051, 256, 133, false, 0) {
+void draw(SkCanvas* canvas) {
+    canvas->clear(SK_ColorWHITE);
+    SkPaint paint;
+    paint.setAntiAlias(true);
+    paint.setColor(0x8055aaff);
+    SkRect clipRect = { 0, 0, 87.4f, 87.4f };
+    for (auto alias: { false, true } ) {
+        canvas->save();
+        canvas->clipRect(clipRect, SkClipOp::kIntersect, alias);
+        canvas->drawCircle(67, 67, 60, paint);
+        canvas->restore();
+        canvas->save();
+        canvas->clipRect(clipRect, SkClipOp::kDifference, alias);
+        canvas->drawCircle(67, 67, 60, paint);
+        canvas->restore();
+        canvas->translate(120, 0);
+    }
+}
+}  // END FIDDLE