Revert of Discard atlas after every MultiPictureDraw::draw

src/gpu/GrLayerCache.cpp

Index: src/gpu/GrLayerCache.cpp
diff --git a/src/gpu/GrLayerCache.cpp b/src/gpu/GrLayerCache.cpp
index b6e4e2e54c62148fba51d1bb11f2cbff0b04a7e1..ccb5bb0be48661de61f055d9960e711bfef883e5 100644
--- a/src/gpu/GrLayerCache.cpp
+++ b/src/gpu/GrLayerCache.cpp
@@ -81,6 +81,7 @@
 
 GrLayerCache::GrLayerCache(GrContext* context)
     : fContext(context) {
+    this->initAtlas();
     memset(fPlotLocks, 0, sizeof(fPlotLocks));
 }
 
@@ -119,6 +120,11 @@
 
     // The atlas only lets go of its texture when the atlas is deleted. 
     fAtlas.free();
+    // GrLayerCache always assumes an atlas exists so recreate it. The atlas 
+    // lazily allocates a replacement texture so reallocating a new 
+    // atlas here won't disrupt a GrContext::abandonContext or freeGpuResources.
+    // TODO: Make GrLayerCache lazily allocate the atlas manager?
+    this->initAtlas();
 }
 
 GrCachedLayer* GrLayerCache::createLayer(uint32_t pictureID, 
@@ -164,7 +170,6 @@
 
     if (layer->locked()) {
         // This layer is already locked
-        SkASSERT(fAtlas);
         SkASSERT(layer->isAtlased());
         SkASSERT(layer->rect().width() == desc.fWidth);
         SkASSERT(layer->rect().height() == desc.fHeight);
@@ -173,19 +178,12 @@
     }
 
     if (layer->isAtlased()) {
-        SkASSERT(fAtlas);
         // Hooray it is still in the atlas - make sure it stays there
         layer->setLocked(true);
         this->incPlotLock(layer->plot()->id());
         *needsRendering = false;
         return true;
     } else {
-        if (!fAtlas) {
-            this->initAtlas();
-            if (!fAtlas) {
-                return false;
-            }
-        }
         // Not in the atlas - will it fit?
         GrPictureInfo* pictInfo = fPictureHash.find(layer->pictureID());
         if (NULL == pictInfo) {
@@ -258,7 +256,7 @@
         this->decPlotLock(plotID);
         // At this point we could aggressively clear out un-locked plots but
         // by delaying we may be able to reuse some of the atlased layers later.
-#if !GR_CACHE_HOISTED_LAYERS
+#if DISABLE_CACHING
         // This testing code aggressively removes the atlased layers. This
         // can be used to separate the performance contribution of less
         // render target pingponging from that due to the re-use of cached layers
@@ -357,7 +355,6 @@
 
 bool GrLayerCache::purgePlot() {
     SkDEBUGCODE(GrAutoValidateCache avc(this);)
-    SkASSERT(fAtlas);
 
     GrAtlas::PlotIter iter;
     GrPlot* plot;
@@ -412,12 +409,7 @@
     plot->resetRects();
 }
 
-#if !GR_CACHE_HOISTED_LAYERS
 void GrLayerCache::purgeAll() {
-    if (!fAtlas) {
-        return;
-    }
-
     GrAtlas::PlotIter iter;
     GrPlot* plot;
     for (plot = fAtlas->iterInit(&iter, GrAtlas::kLRUFirst_IterOrder);
@@ -427,10 +419,7 @@
 
         this->purgePlot(plot);
     }
-
-    fContext->discardRenderTarget(fAtlas->getTexture()->asRenderTarget());
-}
-#endif
+}
 
 class GrPictureDeletionListener : public SkPicture::DeletionListener {
     virtual void onDeletion(uint32_t pictureID) SK_OVERRIDE{
@@ -459,14 +448,12 @@
 #ifdef SK_DEVELOPER
 void GrLayerCache::writeLayersToDisk(const SkString& dirName) {
 
-    if (fAtlas) {
-        GrTexture* atlasTexture = fAtlas->getTexture();
-        if (NULL != atlasTexture) {
-            SkString fileName(dirName);
-            fileName.append("\\atlas.png");
-
-            atlasTexture->surfacePriv().savePixels(fileName.c_str());
-        }
+    GrTexture* atlasTexture = fAtlas->getTexture();
+    if (NULL != atlasTexture) {
+        SkString fileName(dirName);
+        fileName.append("\\atlas.png");
+
+        atlasTexture->surfacePriv().savePixels(fileName.c_str());
     }
 
     SkTDynamicHash<GrCachedLayer, GrCachedLayer::Key>::Iter iter(&fLayerHash);