Cleaning up trailing spaces and typos.

src/core/SkMipMap.cpp

Index: src/core/SkMipMap.cpp
diff --git a/src/core/SkMipMap.cpp b/src/core/SkMipMap.cpp
index c037865fd49b3f25c555a1eb19d5aa217cd8c6bb..e2b2d5d8f7034b5406bccf4f4a2080a1dbc0ae95 100644
--- a/src/core/SkMipMap.cpp
+++ b/src/core/SkMipMap.cpp
@@ -357,7 +357,7 @@ bool SkMipMap::extractLevel(SkScalar scale, Level* levelPtr) const {
     return true;
 }
 
-// Helper which extacts a pixmap from the src bitmap
+// Helper which extracts a pixmap from the src bitmap
 //
 SkMipMap* SkMipMap::Build(const SkBitmap& src, SkDiscardableFactoryProc fact) {
     SkAutoPixmapUnlock srcUnlocker;