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/Bitmap_072.cpp b/docs/examples/Bitmap_072.cpp
new file mode 100644
index 0000000..371535b
--- /dev/null
+++ b/docs/examples/Bitmap_072.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=9b3133a6673d2514d166398adbe1f9f4
+REG_FIDDLE(Bitmap_072, 256, 256, false, 3) {
+void draw(SkCanvas* canvas) {
+    std::vector<int32_t> srcPixels;
+    int width = image->width();
+    int height = image->height();
+    srcPixels.resize(height * width  * 4);
+    SkPixmap pixmap(SkImageInfo::MakeN32Premul(width, height), (const void*) &srcPixels.front(),
+                    width * 4);
+    image->readPixels(pixmap, 0, 0);
+    canvas->scale(.5f, .5f);
+    width /= 4;
+    height /= 4;
+    for (int y = 0; y < 4; ++y) {
+        for (int x = 0; x < 4; ++x) {
+            SkBitmap bitmap;
+            bitmap.allocPixels(SkImageInfo::MakeN32Premul(width, height));
+            bitmap.writePixels(pixmap, -y * width, -x * height);
+            canvas->drawBitmap(bitmap, x * width, y * height);
+        }
+    }
+}
+}  // END FIDDLE