Defer flushes if kPreferNoIO is specified

src/gpu/gl/GrGLRenderTarget.cpp

Index: src/gpu/gl/GrGLRenderTarget.cpp
diff --git a/src/gpu/gl/GrGLRenderTarget.cpp b/src/gpu/gl/GrGLRenderTarget.cpp
index e93c5c100be2a206756e107c675acd10d4bfe072..26c8d4665836ff4063ac4c66e08ba1afc0f0def0 100644
--- a/src/gpu/gl/GrGLRenderTarget.cpp
+++ b/src/gpu/gl/GrGLRenderTarget.cpp
@@ -52,6 +52,8 @@ void GrGLRenderTarget::init(const GrSurfaceDesc& desc, const IDDesc& idDesc) {
     size_t colorBytes = GrBytesPerPixel(fDesc.fConfig);
     SkASSERT(colorBytes > 0);
     fGpuMemorySize = colorValuesPerPixel * fDesc.fWidth * fDesc.fHeight * colorBytes;
+
+    SkASSERT(fGpuMemorySize <= WorseCaseSize(desc));
 }
 
 size_t GrGLRenderTarget::onGpuMemorySize() const {