surfaceflinger: generalize Description::mIsWideGamut

Generalize the mIsWideGamut bool into input and output transfer
functions.  In most cases, the transfer functions are LINEAR,
meaning EOTF() and OETF() are no-op.

Test: manual
Change-Id: I18bfa97ffa950190b553a2ebb18f68b72ab296dd
diff --git a/services/surfaceflinger/RenderEngine/Description.cpp b/services/surfaceflinger/RenderEngine/Description.cpp
index 1b5a466..d70083f 100644
--- a/services/surfaceflinger/RenderEngine/Description.cpp
+++ b/services/surfaceflinger/RenderEngine/Description.cpp
@@ -61,8 +61,12 @@
     return mColorMatrix;
 }
 
-void Description::setWideGamut(bool wideGamut) {
-    mIsWideGamut = wideGamut;
+void Description::setInputTransferFunction(TransferFunction transferFunction) {
+    mInputTransferFunction = transferFunction;
+}
+
+void Description::setOutputTransferFunction(TransferFunction transferFunction) {
+    mOutputTransferFunction = transferFunction;
 }
 
 } /* namespace android */