Canvas.toDataURL to use SkBitmap::readPixels to avoid uninitialized memory

Source/platform/image-encoders/skia/WEBPImageEncoder.cpp

Index: Source/platform/image-encoders/skia/WEBPImageEncoder.cpp
diff --git a/Source/platform/image-encoders/skia/WEBPImageEncoder.cpp b/Source/platform/image-encoders/skia/WEBPImageEncoder.cpp
index 3f00f6797e6132f1ceeb86dd3574aac64f9b9cf1..2b47bea9d4198d8015da502b2b2db6816c3338c5 100644
--- a/Source/platform/image-encoders/skia/WEBPImageEncoder.cpp
+++ b/Source/platform/image-encoders/skia/WEBPImageEncoder.cpp
@@ -56,6 +56,7 @@ static bool rgbPictureImport(const unsigned char* pixels, bool premultiplied, We
     Vector<unsigned char> rgb;
     size_t pixelCount = picture->height * picture->width;
     rgb.reserveInitialCapacity(pixelCount * 3);
+    rgb.resize(pixelCount * 3);

[Stephen White, 2015/07/20 15:33:10]

As discussed, could be cleaner to just put the size in the constructor, and skip
both explicit reserve and resize.

 
     for (unsigned char* data = rgb.data(); pixelCount-- > 0; pixels += 4) {
         unsigned char alpha = pixels[3];