Add auto purging for SkPicture-related Ganesh resources (esp. layers)

src/gpu/SkGpuDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGpuDevice.h"
 
 #include "effects/GrBicubicEffect.h"
@@ skipping 1824 matching lines @@
                  info.width(), info.height());
         return NULL;
     }
 }
 
 SkSurface* SkGpuDevice::newSurface(const SkImageInfo& info) {
     return SkSurface::NewRenderTarget(fContext, info, fRenderTarget->numSamples());
 }
 
 void SkGpuDevice::EXPERIMENTAL_optimize(const SkPicture* picture) {
+    fContext->getLayerCache()->processDeletedPictures();
+
     SkPicture::AccelData::Key key = GPUAccelData::ComputeAccelDataKey();
 
     const SkPicture::AccelData* existing = picture->EXPERIMENTAL_getAccelData(key);
     if (NULL != existing) {
         return;
     }
 
     SkAutoTUnref<GPUAccelData> data(SkNEW_ARGS(GPUAccelData, (key)));
 
     picture->EXPERIMENTAL_addAccelData(data);
 
     GatherGPUInfo(picture, data);
+
+    fContext->getLayerCache()->trackPicture(picture);
 }
 
 static void wrap_texture(GrTexture* texture, int width, int height, SkBitmap* result) {
     SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
     result->setInfo(info);
     result->setPixelRef(SkNEW_ARGS(SkGrPixelRef, (info, texture)))->unref();
 }
 
-void SkGpuDevice::EXPERIMENTAL_purge(const SkPicture* picture) {
-    fContext->getLayerCache()->purge(picture);
-}
-
 bool SkGpuDevice::EXPERIMENTAL_drawPicture(SkCanvas* canvas, const SkPicture* picture) {
+    fContext->getLayerCache()->processDeletedPictures();
 
     SkPicture::AccelData::Key key = GPUAccelData::ComputeAccelDataKey();
 
     const SkPicture::AccelData* data = picture->EXPERIMENTAL_getAccelData(key);
     if (NULL == data) {
         return false;
     }
 
     const GPUAccelData *gpuData = static_cast<const GPUAccelData*>(data);
 
@@ skipping 170 matching lines @@
     playback.draw(canvas, NULL);
 
     // unlock the layers
     for (int i = 0; i < gpuData->numSaveLayers(); ++i) {
         GrCachedLayer* layer = fContext->getLayerCache()->findLayer(picture, i);
         fContext->getLayerCache()->unlock(layer);
     }
 
     return true;
 }