Revert of Add gpu implementation of OverdrawXfermode

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 c2dd8f8a1915376cffcd47e6ccd64d935a14dc27..63739aee814a41a1a4b338d6009590f20eec56d8 100644
--- a/src/utils/debugger/SkDebugCanvas.cpp
+++ b/src/utils/debugger/SkDebugCanvas.cpp
@@ -6,11 +6,55 @@
  */
 
 #include "SkClipStack.h"
+#include "SkColorPriv.h"
 #include "SkDebugCanvas.h"
 #include "SkDrawCommand.h"
 #include "SkDevice.h"
 #include "SkPaintFilterCanvas.h"
-#include "SkOverdrawMode.h"
+#include "SkXfermode.h"
+
+namespace {
+
+class OverdrawXfermode : public SkXfermode {
+public:
+    SkPMColor xferColor(SkPMColor src, SkPMColor dst) const 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)
+        };
+
+
+        int idx;
+        if (SkColorGetR(dst) < 64) { // 0
+            idx = 0;
+        } else if (SkColorGetG(dst) < 25) { // 10
+            idx = 9;  // cap at 9 for upcoming increment
+        } else if ((SkColorGetB(dst)+21)/42 > 0) { // 1-6
+            idx = 7 - (SkColorGetB(dst)+21)/42;
+        } else { // 7-9
+            idx = 10 - (SkColorGetG(dst)+22)/45;
+        }
+        ++idx;
+        SkASSERT(idx < (int)SK_ARRAY_COUNT(gTable));
+
+        return gTable[idx];
+    }
+
+    Factory getFactory() const override { return nullptr; }
+#ifndef SK_IGNORE_TO_STRING
+    void toString(SkString* str) const override { str->set("OverdrawXfermode"); }
+#endif
+};
 
 class DebugPaintFilterCanvas : public SkPaintFilterCanvas {
 public:
@@ -20,7 +64,7 @@
                            bool overrideFilterQuality,
                            SkFilterQuality quality)
         : INHERITED(width, height)
-        , fOverdrawXfermode(overdrawViz ? SkOverdrawMode::Create() : nullptr)
+        , fOverdrawXfermode(overdrawViz ? new OverdrawXfermode : nullptr)
         , fOverrideFilterQuality(overrideFilterQuality)
         , fFilterQuality(quality) {}
 
@@ -54,6 +98,8 @@
 
     typedef SkPaintFilterCanvas INHERITED;
 };
+
+}
 
 SkDebugCanvas::SkDebugCanvas(int width, int height)
         : INHERITED(width, height)