Add support to dump font cache texture for debug purposes

src/gpu/GrTextContext.cpp

Index: src/gpu/GrTextContext.cpp
diff --git a/src/gpu/GrTextContext.cpp b/src/gpu/GrTextContext.cpp
index 1f25c906fbe1d262a57be58352a8de2a5e740d06..7a9df7c8743a2977f3c0c83d36b3dfef9784c333 100644
--- a/src/gpu/GrTextContext.cpp
+++ b/src/gpu/GrTextContext.cpp
@@ -16,11 +16,15 @@
 #include "GrTextStrike.h"
 #include "GrTextStrike_impl.h"
 #include "SkPath.h"
+#include "SkRTConf.h"
 #include "SkStrokeRec.h"
 #include "effects/GrCustomCoordsTextureEffect.h"
 
 static const int kGlyphCoordsAttributeIndex = 1;
 
+SK_CONF_DECLARE(bool, c_DumpFontCache, "gpu.dumpFontCache", false,
+                "Dump the contents of the font cache before every purge.");
+
 void GrTextContext::flushGlyphs() {
     if (NULL == fDrawTarget) {
         return;
@@ -161,6 +165,10 @@ void GrTextContext::drawPackedGlyph(GrGlyph::PackedID packed,
             goto HAS_ATLAS;
         }
 
+        if (c_DumpFontCache) {
+            fContext->getFontCache()->dump();
+        }
+
         // before we purge the cache, we must flush any accumulated draws
         this->flushGlyphs();
         fContext->flush();