Use only one GL context per process, share chaches.

Change-Id: Ieabaa25338d2f4b8d4fd90e7401ad6e7452eae11
diff --git a/libs/hwui/LayerCache.h b/libs/hwui/LayerCache.h
index 2580551..9860994 100644
--- a/libs/hwui/LayerCache.h
+++ b/libs/hwui/LayerCache.h
@@ -43,6 +43,7 @@
 
 class LayerCache: public OnEntryRemoved<LayerSize, Layer*> {
 public:
+    LayerCache();
     LayerCache(uint32_t maxByteSize);
     ~LayerCache();