Bug 1351440 - Part 1. Implement imgDrawingParams. r=jwatt

A struct used during painting to provide input flags to determine how
imagelib draw calls should behave, plus an output DrawResult to return
information about the result of any imagelib draw calls that may have
occurred.

MozReview-Commit-ID: 3jGEh5vEPF

image/DrawResult.h

@@ -84,6 +84,22 @@ operator&=(DrawResult& aLeft, const DrawResult aRight)
   return aLeft;
 }
 
+/**
+ * A struct used during painting to provide input flags to determine how
+ * imagelib draw calls should behave and an output DrawResult to return
+ * information about the result of any imagelib draw calls that may have
+ * occurred.
+ */
+struct imgDrawingParams {
+  explicit imgDrawingParams(uint32_t aImageFlags = 0)
+    : imageFlags(aImageFlags), result(DrawResult::SUCCESS)
+  {}
+
+  const uint32_t imageFlags; // imgIContainer::FLAG_* image flags to pass to
+                             // image lib draw calls.
+  DrawResult result;         // To return results from image lib painting.
+};
+
 } // namespace image
 } // namespace mozilla