Use SkMutex::assertHeld in SkPDFFont and SkPDFShader.

src/pdf/SkPDFFont.cpp

Index: src/pdf/SkPDFFont.cpp
diff --git a/src/pdf/SkPDFFont.cpp b/src/pdf/SkPDFFont.cpp
index 49d383b204ea1f0c25c089fc6ca17efb58ca9db9..c4f013dd37291015c13fefd01472bc0ff1dfb7df 100644
--- a/src/pdf/SkPDFFont.cpp
+++ b/src/pdf/SkPDFFont.cpp
@@ -872,7 +872,8 @@ SkPDFFont* SkPDFFont::getFontSubset(const SkPDFGlyphSet*) {
 
 // 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;
 }