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_029.cpp b/docs/examples/Image_029.cpp
new file mode 100644
index 0000000..c4c2cee
--- /dev/null
+++ b/docs/examples/Image_029.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=8aa8ca63dff4641dfc6ea8a3c555d59c
+REG_FIDDLE(Image_029, 256, 256, false, 3) {
+void draw(SkCanvas* canvas) {
+    canvas->scale(.5f, .5f);
+    const int width = 32;
+    const int height = 32;
+    std::vector<int32_t> dstPixels;
+    dstPixels.resize(height * width * 4);
+    SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
+    for (int y = 0; y < 512; y += height ) {
+        for (int x = 0; x < 512; x += width ) {
+            if (image->readPixels(info, &dstPixels.front(), width * 4, x, y)) {
+                SkPixmap dstPixmap(info, &dstPixels.front(), width * 4);
+                SkBitmap bitmap;
+                bitmap.installPixels(dstPixmap);
+                canvas->drawBitmap(bitmap, 0, 0);
+            }
+            canvas->translate(48, 0);
+        }
+        canvas->translate(-16 * 48, 48);
+    }
+}
+}  // END FIDDLE