PDF: Now threadsafe!

src/pdf/SkPDFCanon.h

Index: src/pdf/SkPDFCanon.h
diff --git a/src/pdf/SkPDFCanon.h b/src/pdf/SkPDFCanon.h
index 7c5cdf70c1ece5ef39e3cabd71dd663b1368ea57..369106ada4c2c6017b9129a01e7562ff9b691de2 100644
--- a/src/pdf/SkPDFCanon.h
+++ b/src/pdf/SkPDFCanon.h
@@ -8,42 +8,33 @@
 #define SkPDFCanon_DEFINED
 
 #include "SkPDFShader.h"
-#include "SkThread.h"
 #include "SkTDArray.h"
 
-struct SkIRect;
 class SkBitmap;
-class SkMatrix;
 class SkPDFFont;
 class SkPDFGraphicState;
 class SkPDFBitmap;
 class SkPaint;
 
-// This class's fields and methods will eventually become part of
-// SkPDFDocument/SkDocument_PDF.  For now, it exists as a singleton to
-// preflight that transition.  This replaces three global arrays in
-// SkPDFFont, SkPDFShader, and SkPDFGraphicsContext.
-//
-// IF YOU ARE LOOKING AT THIS API PLEASE DO NOT WRITE THE CHANGE
-// YOU ARE ABOUT TO WRITE WITHOUT TALKING TO HALCANARY@.
-//
-// Note that this class does not create, delete, reference or
-// dereference the SkPDFObject objects that it indexes.  It is up to
-// the caller to manage the lifetime of these objects.
+/**
+ *  The SkPDFCanon canonicalizes objects across PDF pages(SkPDFDevices).
+ *
+ *  The PDF backend works correctly if:
+ *  -  There is no more than one SkPDFCanon for each thread.
+ *  -  Every SkPDFDevice is given a pointer to a SkPDFCanon on creation.
+ *  -  All SkPDFDevices in a document share the same SkPDFCanon.
+ *  The SkDocument_PDF class makes this happen by owning a single
+ *  SkPDFCanon.
+ *
+ *  Note that this class does not create, delete, reference or
+ *  dereference the SkPDFObject objects that it indexes.  It is up to
+ *  the caller to manage the lifetime of these objects.
+ */
 class SkPDFCanon : SkNoncopyable {
 public:
     SkPDFCanon();
     ~SkPDFCanon();
 
-    static SkPDFCanon& GetCanon();
-
-    // This mutexes will be removed once this class is subsumed into
-    // SkPDFDocument.
-    static SkBaseMutex& GetFontMutex();
-    static SkBaseMutex& GetShaderMutex();
-    static SkBaseMutex& GetPaintMutex();
-    static SkBaseMutex& GetBitmapMutex();
-
     // Returns exact match if there is one.  If not, it returns NULL.
     // If there is no exact match, but there is a related font, we
     // still return NULL, but also set *relatedFont.