drm_hwcomposer: Add Dump() to the Compositor interface

Add a Dump() function to the Compositor base class and pipe it
through hwcomposer. This can be invoked from the shell by
running "dumpsys SurfaceFlinger".

Change-Id: I87646f4e926ac6d52a04ba130957abdfab99c491
Signed-off-by: Sean Paul <seanpaul@chromium.org>
diff --git a/compositor.cpp b/compositor.cpp
index 20f860f..3f85dc7 100644
--- a/compositor.cpp
+++ b/compositor.cpp
@@ -16,6 +16,8 @@
 
 #include "compositor.h"
 
+#include <sstream>
+
 namespace android {
 
 Targeting::~Targeting() {
@@ -27,4 +29,7 @@
 Compositor::~Compositor() {
 }
 
+void Compositor::Dump(std::ostringstream */* out */) const {
+}
+
 }  // namespace android