Orphan ProcXfermode, with an eye towards removing it

src/utils/debugger/SkDebugCanvas.cpp

Index: src/utils/debugger/SkDebugCanvas.cpp
diff --git a/src/utils/debugger/SkDebugCanvas.cpp b/src/utils/debugger/SkDebugCanvas.cpp
index 0f2b9e0f05bf3cda5d883dab6c43a56efb4b8b7f..22eef6f9a5530c78b3ad2e909d9a0c8c56251a80 100644
--- a/src/utils/debugger/SkDebugCanvas.cpp
+++ b/src/utils/debugger/SkDebugCanvas.cpp
@@ -92,37 +92,45 @@ int SkDebugCanvas::getCommandAtPoint(int x, int y, int index) {
     return layer;
 }
 
-static SkPMColor OverdrawXferModeProc(SkPMColor src, SkPMColor dst) {
-    // This table encodes the color progression of the overdraw visualization
-    static const SkPMColor gTable[] = {
-        SkPackARGB32(0x00, 0x00, 0x00, 0x00),
-        SkPackARGB32(0xFF, 128, 158, 255),
-        SkPackARGB32(0xFF, 170, 185, 212),
-        SkPackARGB32(0xFF, 213, 195, 170),
-        SkPackARGB32(0xFF, 255, 192, 127),
-        SkPackARGB32(0xFF, 255, 185, 85),
-        SkPackARGB32(0xFF, 255, 165, 42),
-        SkPackARGB32(0xFF, 255, 135, 0),
-        SkPackARGB32(0xFF, 255,  95, 0),
-        SkPackARGB32(0xFF, 255,  50, 0),
-        SkPackARGB32(0xFF, 255,  0, 0)
-    };
-
-    for (size_t i = 0; i < SK_ARRAY_COUNT(gTable)-1; ++i) {
-        if (gTable[i] == dst) {
-            return gTable[i+1];
+class OverdrawXfermode : public SkXfermode {
+public:
+    virtual SkPMColor xferColor(SkPMColor src, SkPMColor dst) const SK_OVERRIDE {
+        // This table encodes the color progression of the overdraw visualization
+        static const SkPMColor gTable[] = {
+            SkPackARGB32(0x00, 0x00, 0x00, 0x00),
+            SkPackARGB32(0xFF, 128, 158, 255),
+            SkPackARGB32(0xFF, 170, 185, 212),
+            SkPackARGB32(0xFF, 213, 195, 170),
+            SkPackARGB32(0xFF, 255, 192, 127),
+            SkPackARGB32(0xFF, 255, 185, 85),
+            SkPackARGB32(0xFF, 255, 165, 42),
+            SkPackARGB32(0xFF, 255, 135, 0),
+            SkPackARGB32(0xFF, 255,  95, 0),
+            SkPackARGB32(0xFF, 255,  50, 0),
+            SkPackARGB32(0xFF, 255,  0, 0)
+        };
+        
+        for (size_t i = 0; i < SK_ARRAY_COUNT(gTable)-1; ++i) {
+            if (gTable[i] == dst) {
+                return gTable[i+1];
+            }
         }
+        
+        return gTable[SK_ARRAY_COUNT(gTable)-1];
     }
 
-    return gTable[SK_ARRAY_COUNT(gTable)-1];
-}
+    virtual Factory getFactory() const SK_OVERRIDE { return NULL; }
+#ifndef SK_IGNORE_TO_STRING
+    virtual void toString(SkString* str) const { str->set("OverdrawXfermode"); }
+#endif
+};
 
 // The OverdrawFilter modifies every paint to use an SkProcXfermode which
 // in turn invokes OverdrawXferModeProc
 class SkOverdrawFilter : public SkDrawFilter {
 public:
     SkOverdrawFilter() {
-        fXferMode = SkProcXfermode::Create(OverdrawXferModeProc);
+        fXferMode = SkNEW(OverdrawXfermode);
     }
 
     virtual ~SkOverdrawFilter() {