Add setBackdropRenderEffect for View and RenderNode.

support visual effects for backdrop contents of a View or RenderNode.

Test: added unit test & hwui_unit passes
Test: added BackdropBlurActivity in HwAccelerationTest, build & run it

Signed-off-by: Dongya Jiang <jiangdongya@coolpad.com>
Change-Id: If1ac1b8aee53667f175e8fa80ecfc7bdfa28173d
diff --git a/libs/hwui/RenderProperties.cpp b/libs/hwui/RenderProperties.cpp
index 0589f13..c537123 100644
--- a/libs/hwui/RenderProperties.cpp
+++ b/libs/hwui/RenderProperties.cpp
@@ -55,6 +55,12 @@
     return true;
 }
 
+bool LayerProperties::setBackdropImageFilter(SkImageFilter* imageFilter) {
+    if (mBackdropImageFilter.get() == imageFilter) return false;
+    mBackdropImageFilter = sk_ref_sp(imageFilter);
+    return true;
+}
+
 bool LayerProperties::setFromPaint(const SkPaint* paint) {
     bool changed = false;
     changed |= setAlpha(static_cast<uint8_t>(PaintUtils::getAlphaDirect(paint)));
@@ -70,6 +76,7 @@
     setXferMode(other.xferMode());
     setColorFilter(other.getColorFilter());
     setImageFilter(other.getImageFilter());
+    setBackdropImageFilter(other.getBackdropImageFilter());
     mStretchEffect = other.mStretchEffect;
     return *this;
 }