Convert skpCaptureEnabled compile time flag into a property

Convert SkiaPipeline::skpCaptureEnabled into a system property.
Add ability to capture drawing in layers. Add ability to capture
animations/sequence of frames. Fix crash when recording a
TextureView.

Test: Ran capture script.
Change-Id: I463eecf6ec90a601a6cc172ad1901bd4bcc86ac8
diff --git a/libs/hwui/pipeline/skia/LayerDrawable.cpp b/libs/hwui/pipeline/skia/LayerDrawable.cpp
index 3b72a8b..def04e1 100644
--- a/libs/hwui/pipeline/skia/LayerDrawable.cpp
+++ b/libs/hwui/pipeline/skia/LayerDrawable.cpp
@@ -35,6 +35,10 @@
 }
 
 bool LayerDrawable::DrawLayer(GrContext* context, SkCanvas* canvas, Layer* layer) {
+    if (context == nullptr) {
+        SkDEBUGF(("Attempting to draw LayerDrawable into an unsupported surface"));
+        return false;
+    }
     // transform the matrix based on the layer
     SkMatrix layerTransform;
     layer->getTransform().copyTo(layerTransform);