Add Lua SkXfermode skp scraping support

This is to answer the question of do any of our skps have SkLerpXfermodes. AFAICT they should not so this is just to verify.

The only controversial part of this is the addition of 'getLuaName' to SkXfermode

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1614923002

Review URL: https://codereview.chromium.org/1614923002

1 files changed, 40 insertions, 0 deletions

diff --git a/tools/lua/xfer-counter.lua b/tools/lua/xfer-counter.lua
new file mode 100644
index 0000000000..c9d659ceb0
--- /dev/null
+++ b/tools/lua/xfer-counter.lua
@@ -0,0 +1,40 @@
+
+function sk_scrape_startcanvas(c, fileName)
+end
+
+function sk_scrape_endcanvas(c, fileName)
+end
+
+local gXM_Count = 0
+local gXferModeTab = {}
+
+function sk_scrape_accumulate(t)
+    if not t.paint then
+        return
+    end
+
+    local xferMode = t.paint:getXfermode()
+
+    if xferMode then
+        local modeName = xferMode:getTypeName()
+
+        if gXferModeTab[modeName] == nil then
+            gXferModeTab[modeName] = 1;
+        else
+            gXferModeTab[modeName] = gXferModeTab[modeName] + 1
+        end
+        gXM_Count = gXM_Count + 1
+    end
+end
+
+function sk_scrape_summarize()
+    for key,value in pairs(gXferModeTab) do
+        io.write(key, ": ", value, "\n")
+    end
+    io.write("total: ", gXM_Count)
+end
+
+function test_summary()
+    io.write("just testing test_summary\n")
+end
+