skia: add ability to load command_buffer_gles2

src/gpu/GrContextFactory.h

Index: src/gpu/GrContextFactory.h
diff --git a/src/gpu/GrContextFactory.h b/src/gpu/GrContextFactory.h
index 7fd4b77ce0bb2f7e4c6f31c8a4bce5ace05cc540..e2dd635ccfcc042768ab1720ab11529e9fc1c3c1 100644
--- a/src/gpu/GrContextFactory.h
+++ b/src/gpu/GrContextFactory.h
@@ -34,6 +34,9 @@ public:
 #if SK_ANGLE
       kANGLE_GLContextType,
 #endif
+#if SK_COMMAND_BUFFER
+      kCommandBuffer_GLContextType,
+#endif
 #if SK_MESA
       kMESA_GLContextType,
 #endif
@@ -68,6 +71,10 @@ public:
             case kANGLE_GLContextType:
                 return "angle";
 #endif
+#if SK_COMMAND_BUFFER
+            case kCommandBuffer_GLContextType:
+                return "commandbuffer";
+#endif
 #if SK_MESA
             case kMESA_GLContextType:
                 return "mesa";