Add ScreenshotClient functionality for returning GraphicBuffer.

WM and SysUI are interested in screenshotting to GraphicBuffer, for
zero copy initialization of Starting Windows and usage in SysUI. Both
codepaths are co-existing in the WM now, so existing screenshot APIs
are not cleaned up, though perhaps they could be soon.

Test: Manual in combination with other branches.
Bug: 31339431
Change-Id: I11151f44eddbba53559befebf5ee2bde1dee9b40
diff --git a/include/gui/SurfaceComposerClient.h b/include/gui/SurfaceComposerClient.h
index 9352c57..b86c72c 100644
--- a/include/gui/SurfaceComposerClient.h
+++ b/include/gui/SurfaceComposerClient.h
@@ -214,7 +214,13 @@
             Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
             uint32_t minLayerZ, uint32_t maxLayerZ,
             bool useIdentityTransform);
-
+    static status_t captureToBuffer(
+            const sp<IBinder>& display,
+            Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
+            uint32_t minLayerZ, uint32_t maxLayerZ,
+            bool useIdentityTransform,
+            uint32_t rotation,
+            sp<GraphicBuffer>* outbuffer);
 private:
     mutable sp<CpuConsumer> mCpuConsumer;
     mutable sp<IGraphicBufferProducer> mProducer;