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_069.cpp b/docs/examples/Bitmap_069.cpp
new file mode 100644
index 0000000..7da8c49
--- /dev/null
+++ b/docs/examples/Bitmap_069.cpp
@@ -0,0 +1,28 @@
+// 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=b2cbbbbcffb618865d8aae3bc04b2a62
+REG_FIDDLE(Bitmap_069, 256, 128, false, 0) {
+void draw(SkCanvas* canvas) {
+    const int width = 256;
+    const int height = 64;
+    SkImageInfo srcInfo = SkImageInfo::MakeN32Premul(width, height);
+    SkColor  gradColors[] = { 0xFFAA3300, 0x7F881122 };
+    SkPoint  gradPoints[] = { { 0, 0 }, { 256, 0 } };
+    SkPaint paint;
+    paint.setShader(SkGradientShader::MakeLinear(gradPoints, gradColors, nullptr,
+                    SK_ARRAY_COUNT(gradColors), SkShader::kClamp_TileMode));
+    SkBitmap bitmap;
+    bitmap.allocPixels(srcInfo);
+    SkCanvas srcCanvas(bitmap);
+    srcCanvas.drawRect(SkRect::MakeWH(width, height), paint);
+    canvas->drawBitmap(bitmap, 0, 0);
+    SkImageInfo dstInfo = srcInfo.makeColorType(kARGB_4444_SkColorType);
+    std::vector<int16_t> dstPixels;
+    dstPixels.resize(height * width);
+    bitmap.readPixels(dstInfo, &dstPixels.front(), width * 2, 0, 0);
+    SkPixmap dstPixmap(dstInfo, &dstPixels.front(), width * 2);
+    bitmap.installPixels(dstPixmap);
+    canvas->drawBitmap(bitmap, 0, 64);
+}
+}  // END FIDDLE