Added the framework for having canvas/recorder/picture record depth_set's.

tests/CanvasTest.cpp

Index: tests/CanvasTest.cpp
diff --git a/tests/CanvasTest.cpp b/tests/CanvasTest.cpp
index 70c2c04ffabf511239239fe8fe3cf91ab78582af..3c692d0aa626e0efc972623ea8206d29aa6768e5 100644
--- a/tests/CanvasTest.cpp
+++ b/tests/CanvasTest.cpp
@@ -779,6 +779,31 @@ DEF_TEST(Canvas_ClipEmptyPath, reporter) {
     canvas.restore();
 }
 
+
+void test_updatedepth(skiatest::Reporter* reporter) {
+    // set some depths (with picture enabled), then check them as they get set
+    SkPictureRecorder recorder;
+    SkCanvas* canvas;
+    sk_sp<SkPicture> picture;
+
+    canvas = recorder.beginRecording(SkRect::MakeIWH(100, 100));
+
+    canvas->setZ(-10);
+    REPORTER_ASSERT(reporter, canvas->getZ() == -10);
+
+    canvas->save();
+    canvas->setZ(10);
+    REPORTER_ASSERT(reporter, canvas->getZ() == 10);
+
+    canvas->restore();
+    REPORTER_ASSERT(reporter, canvas->getZ() == -10);
+
+    canvas->setZ(3.14);
+    REPORTER_ASSERT(reporter, canvas->getZ() == 3.14);
+
+    recorder.finishRecordingAsPicture();
+}
+
 namespace {
 
 class MockFilterCanvas : public SkPaintFilterCanvas {
@@ -812,4 +837,6 @@ DEF_TEST(PaintFilterCanvas_ConsistentState, reporter) {
     REPORTER_ASSERT(reporter, canvas.getTotalMatrix() == filterCanvas.getTotalMatrix());
     REPORTER_ASSERT(reporter, canvas.getClipBounds(&clip1) == filterCanvas.getClipBounds(&clip2));
     REPORTER_ASSERT(reporter, clip1 == clip2);
+
+    test_updatedepth(reporter);
 }