update canvas doc, primarily readpixels and writepixels

also fixed minor bookmaker bugs so canvas 
include and online docs are (bookmaker detected)
error-free

TBR=reed@google.com
Docs-Preview: https://skia.org/?cl=37840
Bug: skia:
Change-Id: Ifcec9c751105444047c37d89fd984dbd4dfd1913
Reviewed-on: https://skia-review.googlesource.com/37840
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Cary Clark <caryclark@skia.org>
diff --git a/tools/bookmaker/includeParser.cpp b/tools/bookmaker/includeParser.cpp
index 826c321..6aed937 100644
--- a/tools/bookmaker/includeParser.cpp
+++ b/tools/bookmaker/includeParser.cpp
@@ -315,6 +315,7 @@
                 } break;
                 case MarkType::kComment:
                     break;
+                case MarkType::kEnumClass:
                 case MarkType::kEnum: {
                     if (!def) {
                         // work backwards from first word to deduce #Enum name
@@ -366,7 +367,9 @@
                        SkDebugf("enum differs from bmh: %s\n", def->fName.c_str());
                     }
                     for (auto& child : token.fChildren) {
-                        string constName = className + "::" + child->fName;
+                        string constName = MarkType::kEnumClass == token.fMarkType ?
+                                fullName : className;
+                        constName += "::" + child->fName;
                         def = root->find(constName);
                         if (!def) {
                             string innerName = classMapper.first + "::" + child->fName;