Support fp16 in hwui for HDR

Picking sRGB primaries and transfer with extended range bit as the
dataspace, because that's straightforward for EGL.

Then, rather than dimming SDR content, we instead just render as normal
so that we take advantage of the full bit depth

Bug: 236745178
Test: builds
Change-Id: Ica39a2c81be508effb97a8850b0c8e272c10a084
diff --git a/libs/hwui/Properties.cpp b/libs/hwui/Properties.cpp
index ad600d0..6d5b593 100644
--- a/libs/hwui/Properties.cpp
+++ b/libs/hwui/Properties.cpp
@@ -38,6 +38,9 @@
 constexpr bool clip_surfaceviews() {
     return false;
 }
+constexpr bool hdr_10bit_plus() {
+    return false;
+}
 }  // namespace hwui_flags
 #endif
 
@@ -104,6 +107,7 @@
 float Properties::maxHdrHeadroomOn8bit = 5.f;  // TODO: Refine this number
 
 bool Properties::clipSurfaceViews = false;
+bool Properties::hdr10bitPlus = false;
 
 StretchEffectBehavior Properties::stretchEffectBehavior = StretchEffectBehavior::ShaderHWUI;
 
@@ -174,6 +178,7 @@
 
     clipSurfaceViews =
             base::GetBoolProperty("debug.hwui.clip_surfaceviews", hwui_flags::clip_surfaceviews());
+    hdr10bitPlus = hwui_flags::hdr_10bit_plus();
 
     return (prevDebugLayersUpdates != debugLayersUpdates) || (prevDebugOverdraw != debugOverdraw);
 }