Have multiple plotmgrs, one for each mask format.

src/gpu/GrTextStrike.cpp

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrAtlas.h"
 #include "GrGpu.h"
 #include "GrRectanizer.h"
@@ skipping 51 matching lines @@
 
 void GrFontCache::freeAll() {
     fCache.deleteAll();
     delete fAtlasMgr;
     fAtlasMgr = NULL;
     fHead = NULL;
     fTail = NULL;
 }
 
 void GrFontCache::purgeExceptFor(GrTextStrike* preserveStrike) {
+    SkASSERT(NULL != preserveStrike);
     GrTextStrike* strike = fTail;
     bool purge = true;
+    GrMaskFormat maskFormat = preserveStrike->fMaskFormat;
     while (strike) {
-        if (strike == preserveStrike) {
+        if (strike == preserveStrike || maskFormat != strike->fMaskFormat) {
             strike = strike->fPrev;
             continue;
         }
         GrTextStrike* strikeToPurge = strike;
         strike = strikeToPurge->fPrev;
         if (purge) {
             // keep purging if we won't free up any atlases with this strike.
             purge = (NULL == strikeToPurge->fAtlas);
             int index = fCache.slowFindIndex(strikeToPurge);
             SkASSERT(index >= 0);
             fCache.removeAt(index, strikeToPurge->fFontScalerKey->getHash());
             this->detachStrikeFromList(strikeToPurge);
             delete strikeToPurge;
         }
     }
 #if FONT_CACHE_STATS
     ++g_PurgeCount;
 #endif
 }
 
 void GrFontCache::freeAtlasExceptFor(GrTextStrike* preserveStrike) {
+    SkASSERT(NULL != preserveStrike);
     GrTextStrike* strike = fTail;
+    GrMaskFormat maskFormat = preserveStrike->fMaskFormat;
     while (strike) {
-        if (strike == preserveStrike) {
+        if (strike == preserveStrike || maskFormat != strike->fMaskFormat) {
             strike = strike->fPrev;
             continue;
         }
         GrTextStrike* strikeToPurge = strike;
         strike = strikeToPurge->fPrev;
         if (strikeToPurge->removeUnusedAtlases()) {
             if (NULL == strikeToPurge->fAtlas) {
                 int index = fCache.slowFindIndex(strikeToPurge);
                 SkASSERT(index >= 0);
                 fCache.removeAt(index, strikeToPurge->fFontScalerKey->getHash());
@@ skipping 138 matching lines @@
                                            fMaskFormat,
                                            &glyph->fAtlasLocation);
     if (NULL == atlas) {
         return false;
     }
 
     glyph->fAtlas = atlas;
     atlas->setDrawToken(currentDrawToken);
     return true;
 }