Add query for block dimensions of a given format

src/utils/SkTextureCompressor.h

Index: src/utils/SkTextureCompressor.h
diff --git a/src/utils/SkTextureCompressor.h b/src/utils/SkTextureCompressor.h
index 5238ba221be035c78d118b78346dee5fc788f0d6..c6305bab45172c2ca869f9b1ce16bad11f397a1e 100644
--- a/src/utils/SkTextureCompressor.h
+++ b/src/utils/SkTextureCompressor.h
@@ -55,6 +55,12 @@ namespace SkTextureCompressor {
     // RGB source data into an R11 EAC texture, you're gonna have a bad time.
     SkBlitter* CreateBlitterForFormat(int width, int height, void* compressedBuffer,
                                       Format format);
+
+    // Returns the desired dimensions of the block size for the given format. These dimensions
+    // don't necessarily correspond to the hardware-specified dimensions, since there may
+    // be specialized algorithms that operate on multiple blocks at once. These dimensions
+    // reflect that optimization and return the appropriate operable dimensions.
+    void GetBlockDimensions(Format format, int* dimX, int* dimY);
 }
 
 #endif