generate SkColor include

bookmaker can now generate SkColor.h
This required adding support for #define, typedef,
global constexpr, and fixing various bugs, like
forward declared structs between comments.

Docs-Preview: https://skia.org/?cl=131260
Bug: skia:6898
TBR=caryclark@google.com
Change-Id: I6bee0c6f5c3a6820b04472a318abde8a2523dbbb
Reviewed-on: https://skia-review.googlesource.com/131260
Reviewed-by: Cary Clark <caryclark@skia.org>
Commit-Queue: Cary Clark <caryclark@skia.org>
Auto-Submit: Cary Clark <caryclark@skia.org>
diff --git a/docs/SkImage_Reference.bmh b/docs/SkImage_Reference.bmh
index 03dcd16..a6a623f 100644
--- a/docs/SkImage_Reference.bmh
+++ b/docs/SkImage_Reference.bmh
@@ -2012,8 +2012,8 @@
 typedef std::function<void(GrBackendTexture)> BackendTextureReleaseProc;
 ##
 
-Defines a function take one parameter of type
-GrBackendTexture with no return value.
+Defines a callback function, taking one parameter of type GrBackendTexture with
+no return value. Function is called when back-end texture is to be released.
 ##
 
 # ------------------------------------------------------------------------------