Move GrAtlasTextContext to GrDrawingManager, so we only have one.

src/gpu/GrDrawingManager.cpp

Index: src/gpu/GrDrawingManager.cpp
diff --git a/src/gpu/GrDrawingManager.cpp b/src/gpu/GrDrawingManager.cpp
index 9cdc11c82b1bb80a98b5de90fc4cf9288461d006..f4d00dcd3eb27d2ef13c38bd18962df9e3e34569 100644
--- a/src/gpu/GrDrawingManager.cpp
+++ b/src/gpu/GrDrawingManager.cpp
@@ -150,6 +150,14 @@ GrDrawTarget* GrDrawingManager::newDrawTarget(GrRenderTarget* rt) {
     return SkRef(dt);
 }
 
+GrAtlasTextContext* GrDrawingManager::getAtlasTextContext() {
+    if (!fAtlasTextContext) {
+        fAtlasTextContext.reset(GrAtlasTextContext::Create());
+    }
+
+    return fAtlasTextContext.get();
+}
+
 /*
  * This method finds a path renderer that can draw the specified path on
  * the provided target.