Add SkCanvas::writePixels that takes info+pixels directly

src/gpu/SkGpuDevice.cpp

Index: src/gpu/SkGpuDevice.cpp
diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index cf1464a5989a27b621c40c7eed0d24cc60b890f1..4fa48e90447245f4f97312c6df0b14e0de49ec71 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -423,6 +423,21 @@ void SkGpuDevice::writePixels(const SkBitmap& bitmap, int x, int y,
                                config, bitmap.getPixels(), bitmap.rowBytes(), flags);
 }
 
+bool SkGpuDevice::onWritePixelsDirect(const SkImageInfo& info, const void* pixels, size_t rowBytes,
+                                      int x, int y) {
+    // TODO: teach fRenderTarget to take ImageInfo directly to specify the src pixels
+    GrPixelConfig config = SkImageInfo2GrPixelConfig(info.colorType(), info.alphaType());
+    if (kUnknown_GrPixelConfig == config) {
+        return false;
+    }
+    uint32_t flags = 0;
+    if (kUnpremul_SkAlphaType == info.alphaType()) {
+        flags = GrContext::kUnpremul_PixelOpsFlag;
+    }
+    fRenderTarget->writePixels(x, y, info.width(), info.height(), config, pixels, rowBytes, flags);
+    return true;
+}
+
 void SkGpuDevice::onAttachToCanvas(SkCanvas* canvas) {
     INHERITED::onAttachToCanvas(canvas);