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/Image_031.cpp b/docs/examples/Image_031.cpp
new file mode 100644
index 0000000..f513feb
--- /dev/null
+++ b/docs/examples/Image_031.cpp
@@ -0,0 +1,23 @@
+// 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=5949c9a63610cae30019e5b1899ee38f
+REG_FIDDLE(Image_031, 256, 128, false, 3) {
+void draw(SkCanvas* canvas) {
+    std::vector<int32_t> srcPixels;
+    int quarterWidth = image->width() / 16;
+    int rowBytes = quarterWidth * 4;
+    int quarterHeight = image->height() / 16;
+    srcPixels.resize(quarterHeight * rowBytes);
+    SkPixmap pixmap(SkImageInfo::MakeN32Premul(quarterWidth, quarterHeight),
+                    &srcPixels.front(), rowBytes);
+    canvas->scale(4, 4);
+    SkFilterQuality qualities[] = { kNone_SkFilterQuality, kLow_SkFilterQuality,
+                     kMedium_SkFilterQuality, kHigh_SkFilterQuality };
+    for (unsigned index = 0; index < SK_ARRAY_COUNT(qualities); ++index) {
+        image->scalePixels(pixmap, qualities[index]);
+        sk_sp<SkImage> filtered = SkImage::MakeFromRaster(pixmap, nullptr, nullptr);
+        canvas->drawImage(filtered, 16 * index, 0);
+    }
+}
+}  // END FIDDLE