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/Paint_017.cpp b/docs/examples/Paint_017.cpp
new file mode 100644
index 0000000..0fe47e1
--- /dev/null
+++ b/docs/examples/Paint_017.cpp
@@ -0,0 +1,26 @@
+// 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=76d4d4a7931a48495e4d5f54e073be53
+REG_FIDDLE(Paint_017, 256, 256, false, 0) {
+void draw(SkCanvas* canvas) {
+    canvas->clear(0);
+    SkBitmap bm32;
+    bm32.allocPixels(SkImageInfo::Make(20, 10, kN32_SkColorType, kPremul_SkAlphaType));
+    SkCanvas c32(bm32);
+    SkPoint points[] = {{0, 0}, {20, 0}};
+    SkColor colors[] = {0xFF334455, 0xFF662211 };
+    SkPaint paint;
+    paint.setShader(SkGradientShader::MakeLinear(
+                     points, colors, nullptr, SK_ARRAY_COUNT(colors),
+                     SkShader::kClamp_TileMode, 0, nullptr));
+    paint.setDither(true);
+    c32.drawPaint(paint);
+    canvas->scale(12, 12);
+    canvas->drawBitmap(bm32, 0, 0);
+    paint.setBlendMode(SkBlendMode::kPlus);
+    canvas->drawBitmap(bm32, 0, 11, &paint);
+    canvas->drawBitmap(bm32, 0, 11, &paint);
+    canvas->drawBitmap(bm32, 0, 11, &paint);
+}
+}  // END FIDDLE