cc: Don't allocate 0-size discardable memory.

cc/tiles/image_decode_controller.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/tiles/image_decode_controller.h"
 
 #include <stdint.h>
 
 #include "base/macros.h"
 #include "base/memory/discardable_memory.h"
@@ skipping 300 matching lines @@
     bool result = image->readPixels(
         decoded_info, decoded_pixels.get(), decoded_info.minRowBytes(),
         key.src_rect().x(), key.src_rect().y(), SkImage::kAllow_CachingHint);
     DCHECK(result);
   }
 
   SkPixmap decoded_pixmap(decoded_info, decoded_pixels.get(),
                           decoded_info.minRowBytes());
 
   // Now scale the pixels into the destination size.
-  SkImageInfo scaled_info = SkImageInfo::MakeN32Premul(
-      key.target_size().width(), key.target_size().height());
+  // TODO(vmpstr): Once we support skipping images altogether, we can remove
+  // this and skip drawing images that are empty in size. crbug.com/581163
+  const gfx::Size& target_size =
+      key.target_size().IsEmpty() ? gfx::Size(1, 1) : key.target_size();
+  SkImageInfo scaled_info =
+      SkImageInfo::MakeN32Premul(target_size.width(), target_size.height());
   scoped_ptr<base::DiscardableMemory> scaled_pixels;
   {
     TRACE_EVENT0(
         "cc",
         "ImageDecodeController::DecodeImageInternal - allocate scaled pixels");
     scaled_pixels = base::DiscardableMemoryAllocator::GetInstance()
                         ->AllocateLockedDiscardableMemory(
                             scaled_info.minRowBytes() * scaled_info.height());
   }
   SkPixmap scaled_pixmap(scaled_info, scaled_pixels->data(),
@@ skipping 396 matching lines @@
 
 void ImageDecodeController::MemoryBudget::ResetUsage() {
   current_usage_bytes_ = 0;
 }
 
 size_t ImageDecodeController::MemoryBudget::GetCurrentUsageSafe() const {
   return current_usage_bytes_.ValueOrDie();
 }
 
 }  // namespace cc