Add plumbing for HDR WebView

Bug: 279030860
Test: make
Change-Id: Idc7879193c6190a3fadfb46d67fe81eb47101283
diff --git a/libs/hwui/effects/GainmapRenderer.cpp b/libs/hwui/effects/GainmapRenderer.cpp
index bfe4eaf..613f52b 100644
--- a/libs/hwui/effects/GainmapRenderer.cpp
+++ b/libs/hwui/effects/GainmapRenderer.cpp
@@ -38,7 +38,7 @@
 
 using namespace renderthread;
 
-static float getTargetHdrSdrRatio(const SkColorSpace* destColorspace) {
+float getTargetHdrSdrRatio(const SkColorSpace* destColorspace) {
     // We should always have a known destination colorspace. If we don't we must be in some
     // legacy mode where we're lost and also definitely not going to HDR
     if (destColorspace == nullptr) {
diff --git a/libs/hwui/effects/GainmapRenderer.h b/libs/hwui/effects/GainmapRenderer.h
index 4ed2445..0ab03f0 100644
--- a/libs/hwui/effects/GainmapRenderer.h
+++ b/libs/hwui/effects/GainmapRenderer.h
@@ -25,6 +25,8 @@
 
 namespace android::uirenderer {
 
+float getTargetHdrSdrRatio(const SkColorSpace* destColorspace);
+
 void DrawGainmapBitmap(SkCanvas* c, const sk_sp<const SkImage>& image, const SkRect& src,
                        const SkRect& dst, const SkSamplingOptions& sampling, const SkPaint* paint,
                        SkCanvas::SrcRectConstraint constraint,