Gpu Image Decode Controller

cc/tiles/gpu_image_decode_controller.cc

Index: cc/tiles/gpu_image_decode_controller.cc
diff --git a/cc/tiles/gpu_image_decode_controller.cc b/cc/tiles/gpu_image_decode_controller.cc
index da9bd207010071c937c8c6490c1d6511db1b7ab8..0eabcd2e1c33fcb0fbe1a260bfe1011505c73642 100644
--- a/cc/tiles/gpu_image_decode_controller.cc
+++ b/cc/tiles/gpu_image_decode_controller.cc
@@ -4,35 +4,82 @@
 
 #include "cc/tiles/gpu_image_decode_controller.h"
 
+#include "base/memory/discardable_memory_allocator.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/numerics/safe_math.h"
+#include "base/strings/stringprintf.h"
+#include "base/thread_task_runner_handle.h"
 #include "cc/debug/devtools_instrumentation.h"
+#include "cc/output/context_provider.h"
 #include "cc/raster/tile_task_runner.h"
+#include "gpu/command_buffer/client/context_support.h"
+#include "gpu/command_buffer/client/gles2_interface.h"
+#include "gpu_image_decode_controller.h"
 #include "skia/ext/refptr.h"
+#include "skia/ext/texture_handle.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkSurface.h"
+#include "third_party/skia/include/gpu/GrContext.h"
+#include "third_party/skia/include/gpu/GrTexture.h"
+#include "ui/gfx/skia_util.h"
+#include "ui/gl/trace_util.h"
 
 namespace cc {
+namespace {
 
+static const int kMaxGpuImageBytes = 1024 * 1024 * 96;
+static const int kMaxDiscardableItems = 2000;
+
+// Returns true if an image would not be drawn and should therefore be
+// skipped rather than decoded.
+bool SkipImage(const DrawImage& draw_image) {
+  if (!SkIRect::Intersects(draw_image.src_rect(), draw_image.image()->bounds()))
+    return true;
+  if (std::abs(draw_image.scale().width()) <
+          std::numeric_limits<float>::epsilon() ||
+      std::abs(draw_image.scale().height()) <
+          std::numeric_limits<float>::epsilon()) {
+    return true;
+  }
+  return false;
+}
+
+SkImage::DeferredTextureImageUsageParams ParamsFromDrawImage(
+    const DrawImage& draw_image) {
+  SkImage::DeferredTextureImageUsageParams params;
+  params.fMatrix = draw_image.matrix();
+  params.fQuality = draw_image.filter_quality();
+
+  return params;
+}
+
+}  // namespace
+
+// Task which decodes an image and stores the result in discardable memory.
+// This task does not use GPU resources and can be run on any thread.
 class ImageDecodeTaskImpl : public ImageDecodeTask {
  public:
   ImageDecodeTaskImpl(GpuImageDecodeController* controller,
-                      const DrawImage& image,
+                      const DrawImage& draw_image,
                       uint64_t source_prepare_tiles_id)
       : controller_(controller),
-        image_(image),
-        image_ref_(skia::SharePtr(image.image())),
-        source_prepare_tiles_id_(source_prepare_tiles_id) {}
+        image_(draw_image),
+        image_ref_(skia::SharePtr(draw_image.image())),
+        source_prepare_tiles_id_(source_prepare_tiles_id) {
+    DCHECK(!SkipImage(draw_image));
+  }
 
   // Overridden from Task:
   void RunOnWorkerThread() override {
     TRACE_EVENT2("cc", "ImageDecodeTaskImpl::RunOnWorkerThread", "mode", "gpu",
                  "source_prepare_tiles_id", source_prepare_tiles_id_);
-    devtools_instrumentation::ScopedImageDecodeTask image_decode_task(
-        image_ref_.get());
     controller_->DecodeImage(image_);
   }
 
   // Overridden from TileTask:
   void ScheduleOnOriginThread(TileTaskClient* client) override {}
   void CompleteOnOriginThread(TileTaskClient* client) override {
-    controller_->RemovePendingTaskForImage(image_);
+    controller_->DecodeTaskCompleted(image_);
   }
 
  protected:
@@ -42,61 +89,655 @@ class ImageDecodeTaskImpl : public ImageDecodeTask {
   GpuImageDecodeController* controller_;
   DrawImage image_;
   skia::RefPtr<const SkImage> image_ref_;
-  uint64_t source_prepare_tiles_id_;
+  const uint64_t source_prepare_tiles_id_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageDecodeTaskImpl);
 };
 
-GpuImageDecodeController::GpuImageDecodeController() {}
+// Task which creates an image from decoded data. Typically this involves
+// uploading data to the GPU, which requires this task be run on the non-
+// concurrent thread.
+class ImageUploadTaskImpl : public ImageDecodeTask {
+ public:
+  ImageUploadTaskImpl(GpuImageDecodeController* controller,
+                      const DrawImage& draw_image,
+                      scoped_refptr<ImageDecodeTask> decode_dependency,
+                      uint64_t source_prepare_tiles_id)
+      : ImageDecodeTask(std::move(decode_dependency)),
+        controller_(controller),
+        image_(draw_image),
+        image_ref_(skia::SharePtr(draw_image.image())),
+        source_prepare_tiles_id_(source_prepare_tiles_id) {
+    DCHECK(!SkipImage(draw_image));
+  }
+
+  // Override from Task:
+  void RunOnWorkerThread() override {
+    TRACE_EVENT2("cc", "ImageUploadTaskImpl::RunOnWorkerThread", "mode", "gpu",
+                 "source_prepare_tiles_id", source_prepare_tiles_id_);
+    controller_->UploadImage(image_);
+  }
+
+  void ScheduleOnOriginThread(TileTaskClient* client) override {}
+  void CompleteOnOriginThread(TileTaskClient* client) override {
+    controller_->UploadTaskCompleted(image_);
+  }
+
+  // Override from ImageDecodeTask:
+  bool SupportsConcurrentExecution() const override { return false; }
+
+ protected:
+  ~ImageUploadTaskImpl() override {}
+
+ private:
+  GpuImageDecodeController* controller_;
+  DrawImage image_;
+  skia::RefPtr<const SkImage> image_ref_;
+  uint64_t source_prepare_tiles_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(ImageUploadTaskImpl);
+};
+
+GpuImageDecodeController::DecodedImageData::DecodedImageData()
+    : ref_count(0), is_locked(false), decode_failure(false) {}
 
-GpuImageDecodeController::~GpuImageDecodeController() {}
+GpuImageDecodeController::DecodedImageData::~DecodedImageData() = default;
+
+GpuImageDecodeController::UploadedImageData::UploadedImageData()
+    : budgeted(false), ref_count(0) {}
+
+GpuImageDecodeController::UploadedImageData::~UploadedImageData() = default;
+
+GpuImageDecodeController::ImageData::ImageData(DecodedDataMode mode,
+                                               size_t size)
+    : mode(mode), size(size), is_at_raster(false) {}
+
+GpuImageDecodeController::ImageData::~ImageData() = default;
+
+GpuImageDecodeController::GpuImageDecodeController(ContextProvider* context,
+                                                   ResourceFormat decode_format)
+    : format_(decode_format),
+      context_(context),
+      context_threadsafe_proxy_(
+          skia::AdoptRef(context->GrContext()->threadSafeProxy())),
+      image_data_(ImageDataMRUCache::NO_AUTO_EVICT),
+      cached_items_limit_(kMaxDiscardableItems),
+      cached_bytes_limit_(kMaxGpuImageBytes),
+      bytes_used_(0) {}
+
+GpuImageDecodeController::~GpuImageDecodeController() {
+  // SetShouldAggressivelyFreeResources will zero our limits and free all
+  // outstanding image memory.
+  SetShouldAggressivelyFreeResources(true);
+}
 
 bool GpuImageDecodeController::GetTaskForImageAndRef(
-    const DrawImage& image,
+    const DrawImage& draw_image,
     uint64_t prepare_tiles_id,
     scoped_refptr<ImageDecodeTask>* task) {
-  auto image_id = image.image()->uniqueID();
-  base::AutoLock lock(lock_);
-  if (prerolled_images_.count(image_id) != 0) {
+  if (SkipImage(draw_image)) {
     *task = nullptr;
     return false;
   }
 
+  base::AutoLock lock(lock_);
+  const auto image_id = draw_image.image()->uniqueID();
+
+  auto found = image_data_.Get(image_id);
+  if (found != image_data_.end()) {
+    ImageData* image_data = found->second.get();
+    if (image_data->is_at_raster) {
+      // Image is at-raster, just return, this usage will be at-raster as well.
+      *task = nullptr;
+      return false;
+    }
+
+    if (image_data->upload.image) {
+      // The image is already uploaded, ref and return.
+      RefImage(draw_image);
+      *task = nullptr;
+      return true;
+    }
+  }
+
+  // We didn't have a pre-uploaded image, so we need an upload task. Try to find
+  // an existing one.
   scoped_refptr<ImageDecodeTask>& existing_task =
-      pending_image_tasks_[image_id];
-  if (!existing_task) {
-    existing_task = make_scoped_refptr(
-        new ImageDecodeTaskImpl(this, image, prepare_tiles_id));
+      pending_image_upload_tasks_[image_id];
+  if (existing_task) {
+    // We had an existing upload task, ref the image and return the task.
+    RefImage(draw_image);
+    *task = existing_task;
+    return true;
+  }
+
+  // We will be creating a new upload task. If necessary, create a placeholder
+  // ImageData to hold the result.
+  scoped_ptr<ImageData> new_data;
+  ImageData* data;
+  if (found == image_data_.end()) {
+    new_data = CreateImageData(draw_image);
+    data = new_data.get();
+  } else {
+    data = found->second.get();
   }
+
+  // Ensure that the image we're about to decode/upload will fit in memory.
+  if (!EnsureCapacity(data->size)) {
+    // Image will not fit, do an at-raster decode.
+    *task = nullptr;
+    return false;
+  }
+
+  // If we had to create new image data, add it to our map now that we know it
+  // will fit.
+  if (new_data)
+    found = image_data_.Put(image_id, std::move(new_data));
+
+  // Ref image and create a upload and decode tasks. We will release this ref
+  // in UploadTaskCompleted.
+  RefImage(draw_image);
+  existing_task = make_scoped_refptr(new ImageUploadTaskImpl(
+      this, draw_image, GetImageDecodeTaskAndRef(draw_image, prepare_tiles_id),
+      prepare_tiles_id));
+
+  // Ref the image again - this ref is owned by the caller, and it is their
+  // responsibility to release it by calling UnrefImage.
+  RefImage(draw_image);
   *task = existing_task;
-  return false;
+  return true;
 }
 
-void GpuImageDecodeController::UnrefImage(const DrawImage& image) {
-  NOTREACHED();
+void GpuImageDecodeController::UnrefImage(const DrawImage& draw_image) {
+  base::AutoLock lock(lock_);
+  UnrefImageInternal(draw_image);
 }
 
 DecodedDrawImage GpuImageDecodeController::GetDecodedImageForDraw(
     const DrawImage& draw_image) {
-  return DecodedDrawImage(draw_image.image(), draw_image.filter_quality());
+  // We are being called during raster. The context lock must already be
+  // acquired by the caller.
+  context_->GetLock()->AssertAcquired();
+
+  if (SkipImage(draw_image))
+    return DecodedDrawImage(nullptr, draw_image.filter_quality());
+
+  TRACE_EVENT0("cc", "GpuImageDecodeController::GetDecodedImageForDraw");
+
+  base::AutoLock lock(lock_);
+  const uint32_t unique_id = draw_image.image()->uniqueID();
+  auto found = image_data_.Peek(unique_id);
+  if (found == image_data_.end()) {
+    // We didn't find the image, create a new entry.
+    auto data = CreateImageData(draw_image);
+    found = image_data_.Put(unique_id, std::move(data));
+  }
+
+  ImageData* image_data = found->second.get();
+
+  if (!image_data->upload.budgeted) {
+    // If image data is not budgeted by this point, it is at-raster.
+    image_data->is_at_raster = true;
+  }
+
+  // Ref the image and decode so that they stay alive while we are
+  // decoding/uploading.
+  RefImage(draw_image);
+  RefImageDecode(draw_image);
+
+  // We may or may not need to decode and upload the image we've found, the
+  // following functions early-out to if we already decoded.
+  DecodeImageIfNecessary(draw_image, image_data);
+  UploadImageIfNecessary(draw_image, image_data);
+  // Unref the image decode, but not the image. The image ref will be released
+  // in DrawWithImageFinished.
+  UnrefImageDecode(draw_image);
+
+  SkImage* image = image_data->upload.image.get();
+  DCHECK(image || image_data->decode.decode_failure);
+
+  DecodedDrawImage decoded_draw_image(image, draw_image.filter_quality());
+  decoded_draw_image.set_at_raster_decode(image_data->is_at_raster);
+  return decoded_draw_image;
 }
 
 void GpuImageDecodeController::DrawWithImageFinished(
-    const DrawImage& image,
-    const DecodedDrawImage& decoded_image) {}
+    const DrawImage& draw_image,
+    const DecodedDrawImage& decoded_draw_image) {
+  // We are being called during raster. The context lock must already be
+  // acquired by the caller.
+  context_->GetLock()->AssertAcquired();
+
+  if (SkipImage(draw_image))
+    return;
+
+  base::AutoLock lock(lock_);
+  UnrefImageInternal(draw_image);
+
+  // We are mid-draw and holding the context lock, ensure we clean up any
+  // textures (especially at-raster), which may have just been marked for
+  // deletion by UnrefImage.
+  DeletePendingImages();
+}
+
+void GpuImageDecodeController::ReduceCacheUsage() {
+  base::AutoLock lock(lock_);
+  EnsureCapacity(0);
+}
+
+void GpuImageDecodeController::SetShouldAggressivelyFreeResources(
+    bool aggressively_free_resources) {
+  if (aggressively_free_resources) {
+    ContextProvider::ScopedContextLock context_lock(context_);
+    base::AutoLock lock(lock_);
+    // We want to keep as little in our cache as possible. Set our memory limit
+    // to zero and EnsureCapacity to clean up memory.
+    cached_bytes_limit_ = 0;
+    EnsureCapacity(0);
 
-void GpuImageDecodeController::ReduceCacheUsage() {}
+    // We are holding the context lock, so finish cleaning up deleted images
+    // now.
+    DeletePendingImages();
+  } else {
+    base::AutoLock lock(lock_);
+    cached_bytes_limit_ = kMaxGpuImageBytes;
+  }
+}
 
-void GpuImageDecodeController::DecodeImage(const DrawImage& image) {
-  image.image()->preroll();
+void GpuImageDecodeController::DecodeImage(const DrawImage& draw_image) {
   base::AutoLock lock(lock_);
-  prerolled_images_.insert(image.image()->uniqueID());
+  auto found = image_data_.Peek(draw_image.image()->uniqueID());
+  DCHECK(found != image_data_.end());
+  DCHECK(!found->second->is_at_raster);
+  DecodeImageIfNecessary(draw_image, found->second.get());
 }
 
-void GpuImageDecodeController::RemovePendingTaskForImage(
-    const DrawImage& image) {
+void GpuImageDecodeController::UploadImage(const DrawImage& draw_image) {
+  ContextProvider::ScopedContextLock context_lock(context_);
   base::AutoLock lock(lock_);
-  pending_image_tasks_.erase(image.image()->uniqueID());
+  auto found = image_data_.Peek(draw_image.image()->uniqueID());
+  DCHECK(found != image_data_.end());
+  DCHECK(!found->second->is_at_raster);
+  UploadImageIfNecessary(draw_image, found->second.get());
+}
+
+void GpuImageDecodeController::DecodeTaskCompleted(
+    const DrawImage& draw_image) {
+  base::AutoLock lock(lock_);
+  // Decode task is complete, remove it from our list of pending tasks.
+  pending_image_decode_tasks_.erase(draw_image.image()->uniqueID());
+
+  // While the decode task is active, we keep a ref on the decoded data.
+  // Release that ref now.
+  UnrefImageDecode(draw_image);
+}
+
+void GpuImageDecodeController::UploadTaskCompleted(
+    const DrawImage& draw_image) {
+  base::AutoLock lock(lock_);
+  // Upload task is complete, remove it from our list of pending tasks.
+  pending_image_upload_tasks_.erase(draw_image.image()->uniqueID());
+
+  // While the upload task is active, we keep a ref on both the image it will be
+  // populating, as well as the decode it needs to populate it. Release these
+  // refs now.
+  UnrefImageDecode(draw_image);
+  UnrefImageInternal(draw_image);
+}
+
+// Checks if an existing image decode exists. If not, returns a task to produce
+// the requested decode.
+scoped_refptr<ImageDecodeTask>
+GpuImageDecodeController::GetImageDecodeTaskAndRef(const DrawImage& draw_image,
+                                                   uint64_t prepare_tiles_id) {
+  lock_.AssertAcquired();
+
+  const uint32_t image_id = draw_image.image()->uniqueID();
+
+  // This ref is kept alive while an upload task may need this decode. We
+  // release this ref in UploadTaskCompleted.
+  RefImageDecode(draw_image);
+
+  auto found = image_data_.Peek(image_id);
+  if (found != image_data_.end() && found->second->decode.is_locked) {
+    // We should never be creating a decode task for an at raster image.
+    DCHECK(!found->second->is_at_raster);
+    // We should never be creating a decode for an already-uploaded image.
+    DCHECK(!found->second->upload.image);
+    return nullptr;
+  }
+
+  // We didn't have an existing locked image, create a task to lock or decode.
+  scoped_refptr<ImageDecodeTask>& existing_task =
+      pending_image_decode_tasks_[image_id];
+  if (!existing_task) {
+    // Ref image decode and create a decode task. This ref will be released in
+    // DecodeTaskCompleted.
+    RefImageDecode(draw_image);
+    existing_task = make_scoped_refptr(
+        new ImageDecodeTaskImpl(this, draw_image, prepare_tiles_id));
+  }
+  return existing_task;
+}
+
+void GpuImageDecodeController::RefImageDecode(const DrawImage& draw_image) {
+  lock_.AssertAcquired();
+  auto found = image_data_.Peek(draw_image.image()->uniqueID());
+  DCHECK(found != image_data_.end());
+  ++found->second->decode.ref_count;
+  RefCountChanged(found->second.get());
+}
+
+void GpuImageDecodeController::UnrefImageDecode(const DrawImage& draw_image) {
+  lock_.AssertAcquired();
+  auto found = image_data_.Peek(draw_image.image()->uniqueID());
+  DCHECK(found != image_data_.end());
+  DCHECK_GT(found->second->decode.ref_count, 0u);
+  --found->second->decode.ref_count;
+  RefCountChanged(found->second.get());
+}
+
+void GpuImageDecodeController::RefImage(const DrawImage& draw_image) {
+  lock_.AssertAcquired();
+  auto found = image_data_.Peek(draw_image.image()->uniqueID());
+  DCHECK(found != image_data_.end());
+  ++found->second->upload.ref_count;
+  RefCountChanged(found->second.get());
+}
+
+void GpuImageDecodeController::UnrefImageInternal(const DrawImage& draw_image) {
+  lock_.AssertAcquired();
+  auto found = image_data_.Peek(draw_image.image()->uniqueID());
+  DCHECK(found != image_data_.end());
+  DCHECK_GT(found->second->upload.ref_count, 0u);
+  --found->second->upload.ref_count;
+  RefCountChanged(found->second.get());
+}
+
+// Called any time an image or decode ref count changes. Takes care of any
+// necessary memory budget book-keeping and cleanup.
+void GpuImageDecodeController::RefCountChanged(ImageData* image_data) {
+  lock_.AssertAcquired();
+
+  bool has_any_refs =
+      image_data->upload.ref_count > 0 || image_data->decode.ref_count > 0;
+  if (image_data->is_at_raster && !has_any_refs) {
+    // We have an at-raster image which has reached zero refs. If it won't fit
+    // in our cache, delete the image to allow it to fit.
+    if (image_data->upload.image && !CanFitSize(image_data->size)) {
+      images_pending_deletion_.push_back(std::move(image_data->upload.image));
+      image_data->upload.image = nullptr;
+    }
+
+    // We now have an at-raster image which will fit in our cache. Convert it
+    // to not-at-raster.
+    image_data->is_at_raster = false;
+    if (image_data->upload.image) {
+      bytes_used_ += image_data->size;
+      image_data->upload.budgeted = true;
+    }
+  }
+
+  // If we have image refs on a non-at-raster image, it must be budgeted, as it
+  // is either uploaded or pending upload.
+  if (image_data->upload.ref_count > 0 && !image_data->upload.budgeted &&
+      !image_data->is_at_raster) {
+    // We should only be taking non-at-raster refs on images that fit in cache.
+    DCHECK(CanFitSize(image_data->size));
+
+    bytes_used_ += image_data->size;
+    image_data->upload.budgeted = true;
+  }
+
+  // If we have no image refs on an image, it should only be budgeted if it has
+  // an uploaded image. If no image exists (upload was cancelled), we should
+  // un-budget the image.
+  if (image_data->upload.ref_count == 0 && image_data->upload.budgeted &&
+      !image_data->upload.image) {
+    DCHECK_GE(bytes_used_, image_data->size);
+    bytes_used_ -= image_data->size;
+    image_data->upload.budgeted = false;
+  }
+
+  // If we have no decode refs on an image, we should unlock any locked
+  // discardable memory.
+  if (image_data->decode.ref_count == 0 && image_data->decode.is_locked) {
+    DCHECK(image_data->decode.data);
+    image_data->decode.data->Unlock();
+    image_data->decode.is_locked = false;
+  }
+}
+
+// Ensures that we can fit a new image of size |required_size| in our cache. In
+// doing so, this function will free unreferenced image data as necessary to
+// create rooom.
+bool GpuImageDecodeController::EnsureCapacity(size_t required_size) {
+  lock_.AssertAcquired();
+
+  if (CanFitSize(required_size) && !ExceedsPreferredCount())
+    return true;
+
+  // While we are over memory or preferred item capacity, we iterate through
+  // our set of cached image data in LRU order. For each image, we can do two
+  // things: 1) We can free the uploaded image, reducing the memory usage of
+  // the cache and 2) we can remove the entry entirely, reducing the count of
+  // elements in the cache.
+  for (auto it = image_data_.rbegin(); it != image_data_.rend();) {
+    if (it->second->decode.ref_count != 0 ||
+        it->second->upload.ref_count != 0) {
+      ++it;
+      continue;
+    }
+
+    // Current entry has no refs. Ensure it is not locked.
+    DCHECK(!it->second->decode.is_locked);
+
+    // If an image without refs is budgeted, it must have an associated image
+    // upload.
+    DCHECK(!it->second->upload.budgeted || it->second->upload.image);
+
+    // Free the uploaded image if possible.
+    if (it->second->upload.image) {
+      DCHECK(it->second->upload.budgeted);
+      DCHECK_GE(bytes_used_, it->second->size);
+      bytes_used_ -= it->second->size;
+      images_pending_deletion_.push_back(std::move(it->second->upload.image));
+      it->second->upload.image = nullptr;
+      it->second->upload.budgeted = false;
+    }
+
+    // Free the entire entry if necessary.
+    if (ExceedsPreferredCount()) {
+      it = image_data_.Erase(it);
+    } else {
+      ++it;
+    }
+
+    if (CanFitSize(required_size) && !ExceedsPreferredCount())
+      return true;
+  }
+
+  // Preferred count is only used as a guideline when triming the cache. Allow
+  // new elements to be added as long as we are below our size limit.
+  return CanFitSize(required_size);
+}
+
+bool GpuImageDecodeController::CanFitSize(size_t size) const {
+  lock_.AssertAcquired();
+
+  base::CheckedNumeric<uint32_t> new_size(bytes_used_);
+  new_size += size;
+  return new_size.IsValid() && new_size.ValueOrDie() <= cached_bytes_limit_;
+}
+
+bool GpuImageDecodeController::ExceedsPreferredCount() const {
+  lock_.AssertAcquired();
+
+  return image_data_.size() > cached_items_limit_;
+}
+
+void GpuImageDecodeController::DecodeImageIfNecessary(
+    const DrawImage& draw_image,
+    ImageData* image_data) {
+  lock_.AssertAcquired();
+
+  DCHECK_GT(image_data->decode.ref_count, 0u);
+
+  if (image_data->decode.decode_failure) {
+    // We have already tried and failed to decode this image. Don't try again.
+    return;
+  }
+
+  if (image_data->upload.image) {
+    // We already have an uploaded image, no reason to decode.
+    return;
+  }
+
+  if (image_data->decode.data &&
+      (image_data->decode.is_locked || image_data->decode.data->Lock())) {
+    // We already decoded this, or we just needed to lock, early out.
+    image_data->decode.is_locked = true;
+    return;
+  }
+
+  TRACE_EVENT0("cc", "GpuImageDecodeController::DecodeImage");
+
+  image_data->decode.data = nullptr;
+  scoped_ptr<base::DiscardableMemory> backing_memory;

[vmpstr, 2016/04/08 18:24:59]

Probably unique_ptr at this point.

[ericrk, 2016/04/08 20:55:18]

Done.

+  {
+    base::AutoUnlock unlock(lock_);
+    switch (image_data->mode) {
+      case DecodedDataMode::CPU: {
+        backing_memory =
+            base::DiscardableMemoryAllocator::GetInstance()
+                ->AllocateLockedDiscardableMemory(image_data->size);
+        SkImageInfo image_info = CreateImageInfoForDrawImage(draw_image);
+        if (!draw_image.image()->readPixels(image_info, backing_memory->data(),
+                                            image_info.minRowBytes(), 0, 0,
+                                            SkImage::kDisallow_CachingHint)) {
+          backing_memory.reset(nullptr);
+        }
+        break;
+      }
+      case DecodedDataMode::GPU: {
+        backing_memory =
+            base::DiscardableMemoryAllocator::GetInstance()
+                ->AllocateLockedDiscardableMemory(image_data->size);
+        auto params = ParamsFromDrawImage(draw_image);
+        if (!draw_image.image()->getDeferredTextureImageData(
+                *context_threadsafe_proxy_.get(), &params, 1,
+                backing_memory->data())) {
+          backing_memory.reset(nullptr);

[vmpstr, 2016/04/08 18:24:59]

I think just .reset() works

[ericrk, 2016/04/08 20:55:18]

Done.

+        }
+        break;
+      }
+    }
+  }
+
+  if (image_data->decode.data) {
+    // An at-raster task decoded this before us. Ingore our decode.
+    return;
+  }
+
+  if (!backing_memory) {
+    // If |backing_memory| was not populated, we had a non-decodable image.
+    image_data->decode.decode_failure = true;
+    return;
+  }
+
+  image_data->decode.data = std::move(backing_memory);
+  DCHECK(!image_data->decode.is_locked);
+  image_data->decode.is_locked = true;
+}
+
+void GpuImageDecodeController::UploadImageIfNecessary(
+    const DrawImage& draw_image,
+    ImageData* image_data) {
+  context_->GetLock()->AssertAcquired();
+  lock_.AssertAcquired();
+
+  if (image_data->decode.decode_failure) {
+    // We were unnable to decode this image. Don't try to upload.
+    return;
+  }
+
+  if (image_data->upload.image) {
+    // Someone has uploaded this image before us (at raster).
+    return;
+  }
+
+  TRACE_EVENT0("cc", "GpuImageDecodeController::UploadImage");
+  DCHECK(image_data->decode.is_locked);
+  DCHECK_GT(image_data->decode.ref_count, 0u);
+  DCHECK_GT(image_data->upload.ref_count, 0u);
+
+  // We are about to upload a new image and are holding the context lock.
+  // Ensure that any images which have been marked for deletion are actually
+  // cleaned up so we don't exceed our memory limit during this upload.
+  DeletePendingImages();
+
+  skia::RefPtr<SkImage> uploaded_image;
+  {
+    base::AutoUnlock unlock(lock_);
+    switch (image_data->mode) {
+      case DecodedDataMode::CPU: {
+        SkImageInfo image_info = CreateImageInfoForDrawImage(draw_image);
+        uploaded_image = skia::AdoptRef(SkImage::NewFromRaster(
+            image_info, image_data->decode.data->data(),
+            image_info.minRowBytes(), [](const void*, void*) {}, nullptr));
+        break;
+      }
+      case DecodedDataMode::GPU: {
+        uploaded_image =
+            skia::AdoptRef(SkImage::NewFromDeferredTextureImageData(
+                context_->GrContext(), image_data->decode.data->data(),
+                SkBudgeted::kNo));
+        break;
+      }
+    }
+  }
+  DCHECK(uploaded_image);
+
+  // At-raster may have decoded this while we were unlocked. If so, ignore our
+  // result.
+  if (!image_data->upload.image) {
+    image_data->upload.image = std::move(uploaded_image);
+  }
+}
+
+scoped_ptr<GpuImageDecodeController::ImageData>
+GpuImageDecodeController::CreateImageData(const DrawImage& draw_image) {
+  lock_.AssertAcquired();
+
+  DecodedDataMode mode;
+  SkImageInfo info = CreateImageInfoForDrawImage(draw_image);
+  SkImage::DeferredTextureImageUsageParams params =
+      ParamsFromDrawImage(draw_image);
+  size_t data_size = draw_image.image()->getDeferredTextureImageData(
+      *context_threadsafe_proxy_.get(), &params, 1, nullptr);
+
+  if (data_size == 0) {
+    // Can't upload image, too large or other failure. Try to use SW fallback.
+    data_size = info.getSafeSize(info.minRowBytes());
+    mode = DecodedDataMode::CPU;
+  } else {
+    mode = DecodedDataMode::GPU;
+  }
+
+  return make_scoped_ptr(new ImageData(mode, data_size));
+}
+
+void GpuImageDecodeController::DeletePendingImages() {
+  context_->GetLock()->AssertAcquired();
+  lock_.AssertAcquired();
+  images_pending_deletion_.clear();
+}
+
+SkImageInfo GpuImageDecodeController::CreateImageInfoForDrawImage(
+    const DrawImage& draw_image) const {
+  return SkImageInfo::Make(
+      draw_image.image()->width(), draw_image.image()->height(),
+      ResourceFormatToClosestSkColorType(format_), kPremul_SkAlphaType);
 }
 
 }  // namespace cc