change SkDraw and all Blitters to use pixmap instead of bitmap

src/utils/SkTextureCompressor_Blitter.h

Index: src/utils/SkTextureCompressor_Blitter.h
diff --git a/src/utils/SkTextureCompressor_Blitter.h b/src/utils/SkTextureCompressor_Blitter.h
index 73d8ee4ffb362f4fa2937a8dc030ba577b7f74d5..e52237518f3b5840576739e7e6f3f124ed6769b4 100644
--- a/src/utils/SkTextureCompressor_Blitter.h
+++ b/src/utils/SkTextureCompressor_Blitter.h
@@ -368,7 +368,7 @@ public:
     // If the blitter just sets a single value for each pixel, return the
     // bitmap it draws into, and assign value. If not, return NULL and ignore
     // the value parameter.
-    const SkBitmap* justAnOpaqueColor(uint32_t* value) override {
+    const SkPixmap* justAnOpaqueColor(uint32_t* value) override {
         return NULL;
     }