Add medium image quality to software predecode.

cc/tiles/software_image_decode_controller.cc

Index: cc/tiles/software_image_decode_controller.cc
diff --git a/cc/tiles/software_image_decode_controller.cc b/cc/tiles/software_image_decode_controller.cc
index f05bb5d01adb4a5932aa94e9908e3d877fef4c2f..4dc8ae5e63080501bcb2f518b0b6473951155919 100644
--- a/cc/tiles/software_image_decode_controller.cc
+++ b/cc/tiles/software_image_decode_controller.cc
@@ -172,25 +172,6 @@ bool SoftwareImageDecodeController::GetTaskForImageAndRef(
     return false;
   }
 
-  // If we're not going to do a scale, we will just create a task to preroll the
-  // image the first time we see it. This doesn't need to account for memory.
-  // TODO(vmpstr): We can also lock the original sized image, in which case it
-  // does require memory bookkeeping.
-  if (!CanHandleImage(key)) {
-    base::AutoLock lock(lock_);
-    if (prerolled_images_.count(key.image_id()) == 0) {
-      scoped_refptr<ImageDecodeTask>& existing_task = pending_image_tasks_[key];
-      if (!existing_task) {
-        existing_task = make_scoped_refptr(
-            new ImageDecodeTaskImpl(this, key, image, prepare_tiles_id));
-      }
-      *task = existing_task;
-    } else {
-      *task = nullptr;
-    }
-    return false;
-  }
-
   base::AutoLock lock(lock_);
 
   // If we already have the image in cache, then we can return it.
@@ -262,7 +243,6 @@ void SoftwareImageDecodeController::UnrefImage(const DrawImage& image) {
   //       it yet (or failed to decode it).
   //   2b. Unlock the image but keep it in list.
   const ImageKey& key = ImageKey::FromDrawImage(image);
-  DCHECK(CanHandleImage(key)) << key.ToString();
   TRACE_EVENT1("disabled-by-default-cc.debug",
                "SoftwareImageDecodeController::UnrefImage", "key",
                key.ToString());
@@ -293,20 +273,6 @@ void SoftwareImageDecodeController::DecodeImage(const ImageKey& key,
                                                 const DrawImage& image) {
   TRACE_EVENT1("cc", "SoftwareImageDecodeController::DecodeImage", "key",
                key.ToString());
-  if (!CanHandleImage(key)) {
-    image.image()->preroll();
-
-    base::AutoLock lock(lock_);
-    prerolled_images_.insert(key.image_id());
-    // Erase the pending task from the queue, since the task won't be doing
-    // anything useful after this function terminates. Since we don't preroll
-    // images twice, this is actually not necessary but it behaves similar to
-    // the other code path: when this function finishes, the task isn't in the
-    // pending_image_tasks_ list.
-    pending_image_tasks_.erase(key);
-    return;
-  }
-
   base::AutoLock lock(lock_);
   AutoRemoveKeyFromTaskMap remove_key_from_task_map(&pending_image_tasks_, key);
 
@@ -378,8 +344,6 @@ SoftwareImageDecodeController::DecodeImageInternal(
     case kLow_SkFilterQuality:
       return GetOriginalImageDecode(key, *image);
     case kMedium_SkFilterQuality:
-      NOTIMPLEMENTED();
-      return nullptr;
     case kHigh_SkFilterQuality:
       return GetScaledImageDecode(key, *image);
     default:
@@ -398,9 +362,6 @@ DecodedDrawImage SoftwareImageDecodeController::GetDecodedImageForDraw(
   if (key.target_size().IsEmpty())
     return DecodedDrawImage(nullptr, kNone_SkFilterQuality);
 
-  if (!CanHandleImage(key))
-    return DecodedDrawImage(draw_image.image(), draw_image.filter_quality());
-
   return GetDecodedImageForDrawInternal(key, draw_image);
 }
 
@@ -576,8 +537,6 @@ SoftwareImageDecodeController::GetScaledImageDecode(const ImageKey& key,
   }
   SkPixmap scaled_pixmap(scaled_info, scaled_pixels->data(),
                          scaled_info.minRowBytes());
-  // TODO(vmpstr): Start handling more than just high filter quality.
-  DCHECK_EQ(kHigh_SkFilterQuality, key.filter_quality());
   {
     TRACE_EVENT0("disabled-by-default-cc.debug",
                  "SoftwareImageDecodeController::ScaleImage - scale pixels");
@@ -604,7 +563,7 @@ void SoftwareImageDecodeController::DrawWithImageFinished(
                "SoftwareImageDecodeController::DrawWithImageFinished", "key",
                ImageKey::FromDrawImage(image).ToString());
   ImageKey key = ImageKey::FromDrawImage(image);
-  if (!decoded_image.image() || !CanHandleImage(key))
+  if (!decoded_image.image())
     return;
 
   if (decoded_image.is_at_raster_decode())
@@ -671,11 +630,6 @@ void SoftwareImageDecodeController::UnrefAtRasterImage(const ImageKey& key) {
   }
 }
 
-bool SoftwareImageDecodeController::CanHandleImage(const ImageKey& key) {
-  // TODO(vmpstr): Start handling medium filter quality as well.
-  return key.filter_quality() != kMedium_SkFilterQuality;
-}
-
 void SoftwareImageDecodeController::ReduceCacheUsage() {
   TRACE_EVENT0("cc", "SoftwareImageDecodeController::ReduceCacheUsage");
   base::AutoLock lock(lock_);