bitmapshader with A8 bitmap should be colorized by the paint's color

src/gpu/SkGpuDevice.cpp

Index: src/gpu/SkGpuDevice.cpp
diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index ed80c505818d222feb5052a6cd0189865270255f..684e9b45579f06e97ec9c79c8a1582e9020b25d8 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -575,6 +575,13 @@ inline bool skPaint2GrPaintShader(SkGpuDevice* dev,
     if (NULL != effect.get()) {
         grPaint->addColorEffect(effect);
         // Now setup the rest of the paint.
+        // If the shader's bitmap is kA8_Config, the paint's RGB is used, and
+        // modulated by the shader's alpha. Otherwise, the shader's RGB is used,
+        // modulated by the paint's alpha.
+        SkBitmap* bitmap = shader->getBitmap();
+        if (NULL != bitmap && SkBitmap::kA8_Config == bitmap->config()) {
+            return skPaint2GrPaintNoShader(dev, skPaint, false, true, grPaint);
+        }
         return skPaint2GrPaintNoShader(dev, skPaint, true, false, grPaint);
     } else {
         // We still don't have SkColorShader::asNewEffect() implemented.