Plumb through A8 for GL/EGL

Bug: 193170859
Test: TODO

Change-Id: I45993488808457b9a1ea03e9c4a46253d5b45df0
diff --git a/libs/hwui/pipeline/skia/SkiaOpenGLPipeline.cpp b/libs/hwui/pipeline/skia/SkiaOpenGLPipeline.cpp
index 9bca4df..744739a 100644
--- a/libs/hwui/pipeline/skia/SkiaOpenGLPipeline.cpp
+++ b/libs/hwui/pipeline/skia/SkiaOpenGLPipeline.cpp
@@ -91,6 +91,8 @@
         fboInfo.fFormat = GL_RGBA8;
     } else if (colorType == kRGBA_1010102_SkColorType) {
         fboInfo.fFormat = GL_RGB10_A2;
+    } else if (colorType == kAlpha_8_SkColorType) {
+        fboInfo.fFormat = GL_R8;
     } else {
         LOG_ALWAYS_FATAL("Unsupported color type.");
     }