change SkDraw and all Blitters to use pixmap instead of bitmap

src/core/SkAAClip.cpp

Index: src/core/SkAAClip.cpp
diff --git a/src/core/SkAAClip.cpp b/src/core/SkAAClip.cpp
index e55451e3d973e3ceda8f9689c8fd59e255978143..19e94c8c861b2f64ff316e9d421c9c5bbe164e8a 100644
--- a/src/core/SkAAClip.cpp
+++ b/src/core/SkAAClip.cpp
@@ -1297,7 +1297,7 @@ public:
     void blitMask(const SkMask&, const SkIRect& clip) override
         { unexpected(); }
 
-    const SkBitmap* justAnOpaqueColor(uint32_t*) override {
+    const SkPixmap* justAnOpaqueColor(uint32_t*) override {
         return NULL;
     }
 
@@ -2219,6 +2219,6 @@ void SkAAClipBlitter::blitMask(const SkMask& origMask, const SkIRect& clip) {
     } while (y < stopY);
 }
 
-const SkBitmap* SkAAClipBlitter::justAnOpaqueColor(uint32_t* value) {
+const SkPixmap* SkAAClipBlitter::justAnOpaqueColor(uint32_t* value) {
     return NULL;
 }