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/AutoCanvasRestore_001.cpp b/docs/examples/AutoCanvasRestore_001.cpp
new file mode 100644
index 0000000..6176b86
--- /dev/null
+++ b/docs/examples/AutoCanvasRestore_001.cpp
@@ -0,0 +1,22 @@
+// 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=9f459b218ec079c1ada23f4412968f9a
+REG_FIDDLE(AutoCanvasRestore_001, 256, 256, true, 0) {
+void draw(SkCanvas* canvas) {
+    for (bool callRestore : { false, true } ) {
+        for (bool saveCanvas : {false, true} ) {
+            SkAutoCanvasRestore autoRestore(canvas, saveCanvas);
+            if (!saveCanvas) {
+                canvas->save();
+            }
+            SkDebugf("saveCanvas: %s  before restore: %d\n",
+                   saveCanvas ? "true" : "false", canvas->getSaveCount());
+            if (callRestore) autoRestore.restore();
+            SkDebugf("saveCanvas: %s  after restore: %d\n",
+                   saveCanvas ? "true" : "false", canvas->getSaveCount());
+        }
+    }
+    SkDebugf("final count: %d\n", canvas->getSaveCount());
+}
+}  // END FIDDLE