Don't copy image buffer when calculating size.

src/core/SkImageCacherator.cpp

Index: src/core/SkImageCacherator.cpp
diff --git a/src/core/SkImageCacherator.cpp b/src/core/SkImageCacherator.cpp
index 496ca74d9a1870a9195256b9b8cc43cc5f5dc235..f12123195c3d8e22cdf67177fe029126d0b393d8 100644
--- a/src/core/SkImageCacherator.cpp
+++ b/src/core/SkImageCacherator.cpp
@@ -127,6 +127,13 @@ bool SkImageCacherator::directGeneratePixels(const SkImageInfo& info, void* pixe
     return generator->getPixels(info, pixels, rb);
 }
 
+bool SkImageCacherator::canGenerateTexture(const GrContextThreadSafeProxy& proxy)
+{
+    ScopedGenerator generator(this);
+    return generator->canGenerateTexture(proxy);
+}
+
+
 //////////////////////////////////////////////////////////////////////////////////////////////////
 
 bool SkImageCacherator::lockAsBitmapOnlyIfAlreadyCached(SkBitmap* bitmap) {