Use SkMutex::assertHeld in SkPDFFont and SkPDFShader.

src/pdf/SkPDFFont.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <ctype.h>
 
 #include "SkData.h"
@@ skipping 854 matching lines @@
     CanonicalFonts().push(newEntry);
     return font;  // Return the reference new SkPDFFont() created.
 }
 
 SkPDFFont* SkPDFFont::getFontSubset(const SkPDFGlyphSet*) {
     return NULL;  // Default: no support.
 }
 
 // static
 SkTDArray<SkPDFFont::FontRec>& SkPDFFont::CanonicalFonts() {
-    // This initialization is only thread safe with gcc.
+    SkPDFFont::CanonicalFontsMutex().assertHeld();
+    // This initialization is only thread safe with gcc, so hold the mutex.

[mtklein, 2014/06/20 17:40:54]

It's not even safe in Chromium.  They disable the feature that makes it so. 
Maybe just delete the comments?

[hal.canary, 2014/06/20 17:49:06]

Done.

     static SkTDArray<FontRec> gCanonicalFonts;
     return gCanonicalFonts;
 }
 
 // static
 SkBaseMutex& SkPDFFont::CanonicalFontsMutex() {
     // This initialization is only thread safe with gcc, or when
     // POD-style mutex initialization is used.
     SK_DECLARE_STATIC_MUTEX(gCanonicalFontsMutex);
     return gCanonicalFontsMutex;
@@ skipping 589 matching lines @@
 
     insert("FontBBox", makeFontBBox(bbox, 1000))->unref();
     insertInt("FirstChar", 1);
     insertInt("LastChar", lastGlyphID() - firstGlyphID() + 1);
     insert("Widths", widthArray.get());
     insertName("CIDToGIDMap", "Identity");
 
     populateToUnicodeTable(NULL);
     return true;
 }