Revert of Restore text alloc optimizations. (patchset #4 of https://codereview.chromium.org/466363009/)

Reason for revert:
GM failures on http://108.170.220.120:10115/builders/Test-Ubuntu12-ShuttleA-GTX660-x86-Release/builds/1867/

Original issue's description:
> Restore text vertex buffer alloc and other optimizations.
>
> Modifies the fontcache GM to ensure that the font cache is forced to flush.
>
> Committed: https://skia.googlesource.com/skia/+/9c3d24b9d1ba3d955094ff0cb1ba2d11e1c1adca

R=bsalomon@google.com, robertphillips@google.com, jvanverth@google.com
TBR=bsalomon@google.com, jvanverth@google.com, robertphillips@google.com
NOTREECHECKS=true
NOTRY=true

Author: djsollen@google.com

Review URL: https://codereview.chromium.org/510103003
diff --git a/src/gpu/GrDistanceFieldTextContext.cpp b/src/gpu/GrDistanceFieldTextContext.cpp
index 9cf53ce..b7b4f99 100755
--- a/src/gpu/GrDistanceFieldTextContext.cpp
+++ b/src/gpu/GrDistanceFieldTextContext.cpp
@@ -56,20 +56,24 @@
 GrDistanceFieldTextContext::GrDistanceFieldTextContext(GrContext* context,
                                                        const SkDeviceProperties& properties,
                                                        bool enable)
-                                                    : GrTextContext(context, properties)
-                                                    , fStrike(NULL)
+                                                    : GrTextContext(context, properties) {
 #if SK_FORCE_DISTANCEFIELD_FONTS
-                                                    , fEnableDFRendering(true)
+    fEnableDFRendering = true;
 #else
-                                                    , fEnableDFRendering(true)//enable)
+    fEnableDFRendering = enable;
 #endif
-                                                    , fEffectTextureUniqueID(SK_InvalidUniqueID)
-                                                    , fEffectColor(GrColor_ILLEGAL)
-                                                    , fEffectFlags(0)
-                                                    , fGammaTexture(NULL)
-                                                    , fVertices(NULL)
-                                                    , fVertexCount(0)
-                                                    , fCurrVertex(0) {
+    fStrike = NULL;
+    fGammaTexture = NULL;
+
+    fCurrTexture = NULL;
+    fCurrVertex = 0;
+    fEffectTextureUniqueID = SK_InvalidUniqueID;
+    fEffectColor = GrColor_ILLEGAL;
+    fEffectFlags = 0;
+
+    fVertices = NULL;
+    fMaxVertices = 0;
+
     fVertexBounds.setLargestInverted();
 }
 
@@ -118,9 +122,7 @@
     GrTextureParams params(SkShader::kRepeat_TileMode, GrTextureParams::kBilerp_FilterMode);
     GrTextureParams gammaParams(SkShader::kClamp_TileMode, GrTextureParams::kNone_FilterMode);
     
-    GrTexture* currTexture = fStrike->getTexture();
-    SkASSERT(currTexture);
-    uint32_t textureUniqueID = currTexture->getUniqueID();
+    uint32_t textureUniqueID = fCurrTexture->getUniqueID();
     
     // set up any flags
     uint32_t flags = 0;
@@ -138,7 +140,7 @@
         flags != fEffectFlags) {
         if (fUseLCDText) {
             GrColor colorNoPreMul = skcolor_to_grcolor_nopremultiply(filteredColor);
-            fCachedEffect.reset(GrDistanceFieldLCDTextureEffect::Create(currTexture,
+            fCachedEffect.reset(GrDistanceFieldLCDTextureEffect::Create(fCurrTexture,
                                                                         params,
                                                                         fGammaTexture,
                                                                         gammaParams,
@@ -148,7 +150,7 @@
 #ifdef SK_GAMMA_APPLY_TO_A8
             U8CPU lum = SkColorSpaceLuminance::computeLuminance(fDeviceProperties.fGamma,
                                                                 filteredColor);
-            fCachedEffect.reset(GrDistanceFieldTextureEffect::Create(currTexture,
+            fCachedEffect.reset(GrDistanceFieldTextureEffect::Create(fCurrTexture,
                                                                      params,
                                                                      fGammaTexture,
                                                                      gammaParams,
@@ -224,17 +226,26 @@
         fDrawTarget->drawIndexedInstances(kTriangles_GrPrimitiveType,
                                           nGlyphs,
                                           4, 6, &fVertexBounds);
+        fDrawTarget->resetVertexSource();
+        fVertices = NULL;
+        fMaxVertices = 0;
         fCurrVertex = 0;
+        SkSafeSetNull(fCurrTexture);
         fVertexBounds.setLargestInverted();
     }
-    
-    fDrawTarget->resetVertexSource();
-    fVertices = NULL;
 }
 
 void GrDistanceFieldTextContext::drawPackedGlyph(GrGlyph::PackedID packed,
                                                  SkFixed vx, SkFixed vy,
                                                  GrFontScaler* scaler) {
+    if (NULL == fDrawTarget) {
+        return;
+    }
+    
+    if (NULL == fStrike) {
+        fStrike = fContext->getFontCache()->getStrike(scaler, true);
+    }
+    
     GrGlyph* glyph = fStrike->getGlyph(packed, scaler);
     if (NULL == glyph || glyph->fBounds.isEmpty()) {
         return;
@@ -278,19 +289,10 @@
 #endif
         }
 
-        // flush any accumulated draws to allow us to free up a plot
-        int remainingVertexCount = fVertexCount - fCurrVertex;
+        // before we purge the cache, we must flush any accumulated draws
         this->flushGlyphs();
         fContext->flush();
 
-        // need to reallocate the vertex buffer for the remaining glyphs
-        fVertexCount = remainingVertexCount;
-        bool success = fDrawTarget->reserveVertexAndIndexSpace(fVertexCount,
-                                                               0,
-                                                               &fVertices,
-                                                               NULL);
-        GrAlwaysAssert(success);
-
         // we should have an unused plot now
         if (fContext->getFontCache()->freeUnusedPlot(fStrike) &&
             fStrike->addGlyphToAtlas(glyph, scaler)) {
@@ -326,6 +328,55 @@
     GrTexture* texture = glyph->fPlot->texture();
     SkASSERT(texture);
 
+    if (fCurrTexture != texture || fCurrVertex + 4 > fMaxVertices) {
+        this->flushGlyphs();
+        fCurrTexture = texture;
+        fCurrTexture->ref();
+    }
+
+    bool useColorVerts = !fUseLCDText;
+    
+    if (NULL == fVertices) {
+        // If we need to reserve vertices allow the draw target to suggest
+        // a number of verts to reserve and whether to perform a flush.
+        fMaxVertices = kMinRequestedVerts;
+        if (useColorVerts) {
+            fDrawTarget->drawState()->setVertexAttribs<gTextVertexWithColorAttribs>(
+                                                    SK_ARRAY_COUNT(gTextVertexWithColorAttribs));
+        } else {
+            fDrawTarget->drawState()->setVertexAttribs<gTextVertexAttribs>(
+                                                    SK_ARRAY_COUNT(gTextVertexAttribs));
+        }
+        bool flush = fDrawTarget->geometryHints(&fMaxVertices, NULL);
+        if (flush) {
+            this->flushGlyphs();
+            fContext->flush();
+            if (useColorVerts) {
+                fDrawTarget->drawState()->setVertexAttribs<gTextVertexWithColorAttribs>(
+                                                    SK_ARRAY_COUNT(gTextVertexWithColorAttribs));
+            } else {
+                fDrawTarget->drawState()->setVertexAttribs<gTextVertexAttribs>(
+                                                    SK_ARRAY_COUNT(gTextVertexAttribs));
+            }
+        }
+        fMaxVertices = kDefaultRequestedVerts;
+        // ignore return, no point in flushing again.
+        fDrawTarget->geometryHints(&fMaxVertices, NULL);
+        
+        int maxQuadVertices = 4 * fContext->getQuadIndexBuffer()->maxQuads();
+        if (fMaxVertices < kMinRequestedVerts) {
+            fMaxVertices = kDefaultRequestedVerts;
+        } else if (fMaxVertices > maxQuadVertices) {
+            // don't exceed the limit of the index buffer
+            fMaxVertices = maxQuadVertices;
+        }
+        bool success = fDrawTarget->reserveVertexAndIndexSpace(fMaxVertices,
+                                                               0,
+                                                               &fVertices,
+                                                               NULL);
+        GrAlwaysAssert(success);
+    }
+    
     SkScalar dx = SkIntToScalar(glyph->fBounds.fLeft + SK_DistanceFieldInset);
     SkScalar dy = SkIntToScalar(glyph->fBounds.fTop + SK_DistanceFieldInset);
     SkScalar width = SkIntToScalar(glyph->fBounds.width() - 2*SK_DistanceFieldInset);
@@ -338,7 +389,7 @@
     sy += dy;
     width *= scale;
     height *= scale;
-
+    
     SkFixed tx = SkIntToFixed(glyph->fAtlasLocation.fX + SK_DistanceFieldInset);
     SkFixed ty = SkIntToFixed(glyph->fAtlasLocation.fY + SK_DistanceFieldInset);
     SkFixed tw = SkIntToFixed(glyph->fBounds.width() - 2*SK_DistanceFieldInset);
@@ -369,7 +420,7 @@
                               SkFixedToFloat(texture->normalizeFixedX(tx + tw)),
                               SkFixedToFloat(texture->normalizeFixedY(ty + th)),
                               vertSize);
-    if (!fUseLCDText) {
+    if (useColorVerts) {
         if (0xFF == GrColorUnpackA(fPaint.getColor())) {
             fDrawTarget->drawState()->setHint(GrDrawState::kVertexColorsAreOpaque_Hint, true);
         }
@@ -459,23 +510,6 @@
     }
 }
 
-void GrDistanceFieldTextContext::allocateVertices(const char text[], size_t byteLength) {
-    SkASSERT(NULL == fVertices);
-    if (!fUseLCDText) {
-        fDrawTarget->drawState()->setVertexAttribs<gTextVertexWithColorAttribs>(
-                                                    SK_ARRAY_COUNT(gTextVertexWithColorAttribs));
-    } else {
-        fDrawTarget->drawState()->setVertexAttribs<gTextVertexAttribs>(
-                                                    SK_ARRAY_COUNT(gTextVertexAttribs));
-    }
-    fVertexCount = 4*fSkPaint.textToGlyphs(text, byteLength, NULL);
-    bool success = fDrawTarget->reserveVertexAndIndexSpace(fVertexCount,
-                                                           0,
-                                                           &fVertices,
-                                                           NULL);
-    GrAlwaysAssert(success);
-}
-
 void GrDistanceFieldTextContext::drawText(const GrPaint& paint, const SkPaint& skPaint,
                                           const char text[], size_t byteLength,
                                           SkScalar x, SkScalar y) {
@@ -489,10 +523,6 @@
 
     this->init(paint, skPaint);
 
-    if (NULL == fDrawTarget) {
-        return;
-    }
-    
     SkScalar sizeRatio = fTextRatio;
 
     SkDrawCacheProc glyphCacheProc = fSkPaint.getDrawCacheProc();
@@ -500,14 +530,9 @@
     SkAutoGlyphCacheNoGamma    autoCache(fSkPaint, &fDeviceProperties, NULL);
     SkGlyphCache*              cache = autoCache.getCache();
     GrFontScaler*              fontScaler = GetGrFontScaler(cache);
-    if (NULL == fStrike) {
-        fStrike = fContext->getFontCache()->getStrike(fontScaler, true);
-    }
 
     setup_gamma_texture(fContext, cache, fDeviceProperties, &fGammaTexture);
 
-    this->allocateVertices(text, byteLength);
-
     // need to measure first
     // TODO - generate positions and pre-load cache as well?
     const char* stop = text + byteLength;
@@ -575,23 +600,14 @@
 
     this->init(paint, skPaint);
 
-    if (NULL == fDrawTarget) {
-        return;
-    }
-    
     SkDrawCacheProc glyphCacheProc = fSkPaint.getDrawCacheProc();
 
     SkAutoGlyphCacheNoGamma    autoCache(fSkPaint, &fDeviceProperties, NULL);
     SkGlyphCache*              cache = autoCache.getCache();
     GrFontScaler*              fontScaler = GetGrFontScaler(cache);
-    if (NULL == fStrike) {
-        fStrike = fContext->getFontCache()->getStrike(fontScaler, true);
-    }
 
     setup_gamma_texture(fContext, cache, fDeviceProperties, &fGammaTexture);
 
-    this->allocateVertices(text, byteLength);
-
     const char*        stop = text + byteLength;
 
     if (SkPaint::kLeft_Align == fSkPaint.getTextAlign()) {