[SurfaceFlinger] add getDisplayedContentSamplingAttributes i/f

Add interface to ISurfaceComposer that can query the
graphics.composer for querying the displayed content sampling
engine's supported attributes.

Bug: 116028618
Test: Boot
Test: ran test client against prototype, see attributes reported
Test: Ran new test './libgui_test  --gtest_filter="DisplayedContentSamp*"'
Test: on hwc with and without new function hook.
Change-Id: Ie4bebd98d134e63a9f3e21f79ae519a1fe8055b0
diff --git a/libs/gui/SurfaceComposerClient.cpp b/libs/gui/SurfaceComposerClient.cpp
index 87c6f27..41e5abb 100644
--- a/libs/gui/SurfaceComposerClient.cpp
+++ b/libs/gui/SurfaceComposerClient.cpp
@@ -1077,6 +1077,15 @@
             outCapabilities);
 }
 
+status_t SurfaceComposerClient::getDisplayedContentSamplingAttributes(const sp<IBinder>& display,
+                                                                      ui::PixelFormat* outFormat,
+                                                                      ui::Dataspace* outDataspace,
+                                                                      uint8_t* outComponentMask) {
+    return ComposerService::getComposerService()
+            ->getDisplayedContentSamplingAttributes(display, outFormat, outDataspace,
+                                                    outComponentMask);
+}
+
 // ----------------------------------------------------------------------------
 
 status_t ScreenshotClient::capture(const sp<IBinder>& display, const ui::Dataspace reqDataSpace,