New approach for GPU font atlas

src/gpu/GrBitmapTextContext.cpp

Index: src/gpu/GrBitmapTextContext.cpp
diff --git a/src/gpu/GrBitmapTextContext.cpp b/src/gpu/GrBitmapTextContext.cpp
index 4f43c758992e0936220444307c22efb758752ff5..f2a6d95cb8c7f04c0221862f4743a7a1ac93be9a 100755
--- a/src/gpu/GrBitmapTextContext.cpp
+++ b/src/gpu/GrBitmapTextContext.cpp
@@ -518,13 +518,13 @@ void GrBitmapTextContext::drawPackedGlyph(GrGlyph::PackedID packed,
     }
 
     if (NULL == glyph->fPlot) {
-        if (fStrike->getGlyphAtlas(glyph, scaler)) {
+        if (fStrike->addGlyphToAtlas(glyph, scaler)) {
             goto HAS_ATLAS;
         }
 
         // try to clear out an unused plot before we flush
-        fContext->getFontCache()->freePlotExceptFor(fStrike);
-        if (fStrike->getGlyphAtlas(glyph, scaler)) {
+        if (fContext->getFontCache()->freeUnusedPlot(fStrike) &&
+            fStrike->addGlyphToAtlas(glyph, scaler)) {
             goto HAS_ATLAS;
         }
 
@@ -534,14 +534,13 @@ void GrBitmapTextContext::drawPackedGlyph(GrGlyph::PackedID packed,
 #endif
         }
 
-        // before we purge the cache, we must flush any accumulated draws
+        // flush any accumulated draws to allow us to free up a plot
         this->flushGlyphs();
         fContext->flush();
 
-        // try to purge
-        fContext->getFontCache()->purgeExceptFor(fStrike);
-        // need to use new flush count here
-        if (fStrike->getGlyphAtlas(glyph, scaler)) {
+        // we should have an unused plot now
+        if (fContext->getFontCache()->freeUnusedPlot(fStrike) &&
+            fStrike->addGlyphToAtlas(glyph, scaler)) {
             goto HAS_ATLAS;
         }