Split image decode cache limits into "working set" vs "cache" limits

cc/tiles/gpu_image_decode_cache.h

Index: cc/tiles/gpu_image_decode_cache.h
diff --git a/cc/tiles/gpu_image_decode_cache.h b/cc/tiles/gpu_image_decode_cache.h
index a48624d6ef4c122301cec1c6bc77ef7bf0c03c2b..c80c5a9b43ccca53b1b67e760c27fc7d29e213f0 100644
--- a/cc/tiles/gpu_image_decode_cache.h
+++ b/cc/tiles/gpu_image_decode_cache.h
@@ -103,7 +103,8 @@ class CC_EXPORT GpuImageDecodeCache
 
   explicit GpuImageDecodeCache(ContextProvider* context,
                                ResourceFormat decode_format,
-                               size_t max_gpu_image_bytes);
+                               size_t max_working_set_bytes,
+                               size_t max_cache_bytes);
   ~GpuImageDecodeCache() override;
 
   // ImageDecodeCache overrides.
@@ -142,8 +143,9 @@ class CC_EXPORT GpuImageDecodeCache
   void OnImageUploadTaskCompleted(const DrawImage& image);
 
   // For testing only.
-  void SetCachedBytesLimitForTesting(size_t limit) {
+  void SetAllByteLimitsForTesting(size_t limit) {
     cached_bytes_limit_ = limit;
+    max_working_set_bytes_ = limit;
   }
   size_t GetBytesUsedForTesting() const { return bytes_used_; }
   size_t GetNumCacheEntriesForTesting() const {
@@ -292,10 +294,11 @@ class CC_EXPORT GpuImageDecodeCache
   // to ref-count or to orphaned status.
   void OwnershipChanged(const DrawImage& draw_image, ImageData* image_data);
 
-  // Ensures that the cache can hold an element of |required_size|, freeing
-  // unreferenced cache entries if necessary to make room.
+  // Ensures that the working set can hold an element of |required_size|,
+  // freeing unreferenced cache entries to make room.
   bool EnsureCapacity(size_t required_size);
-  bool CanFitSize(size_t size) const;
+  bool CanFitInWorkingSet(size_t size) const;
+  bool CanFitInCache(size_t size) const;
   bool ExceedsPreferredCount() const;
 
   void DecodeImageIfNecessary(const DrawImage& draw_image,
@@ -337,8 +340,9 @@ class CC_EXPORT GpuImageDecodeCache
   using InUseCache = std::unordered_map<InUseCacheKey, InUseCacheEntry>;
   InUseCache in_use_cache_;
 
-  const size_t normal_max_gpu_image_bytes_;
-  size_t cached_bytes_limit_ = normal_max_gpu_image_bytes_;
+  size_t max_working_set_bytes_;
+  const size_t normal_max_cache_bytes_;
+  size_t cached_bytes_limit_ = normal_max_cache_bytes_;
   size_t bytes_used_ = 0;
   base::MemoryState memory_state_ = base::MemoryState::NORMAL;