cc: Plumb gpu/sw image decode limits as layer tree settings.

cc/tiles/software_image_decode_controller.h

Index: cc/tiles/software_image_decode_controller.h
diff --git a/cc/tiles/software_image_decode_controller.h b/cc/tiles/software_image_decode_controller.h
index 14632aad610572e547c5e60294eedd08af152a9b..e27ef15a6870928fdea1e53b6882438465211bc6 100644
--- a/cc/tiles/software_image_decode_controller.h
+++ b/cc/tiles/software_image_decode_controller.h
@@ -103,8 +103,8 @@ class CC_EXPORT SoftwareImageDecodeController
   using ImageKey = ImageDecodeControllerKey;
   using ImageKeyHash = ImageDecodeControllerKeyHash;
 
-  explicit SoftwareImageDecodeController(ResourceFormat format);
-  SoftwareImageDecodeController();
+  SoftwareImageDecodeController(ResourceFormat format,
+                                size_t locked_memory_limit_bytes);
   ~SoftwareImageDecodeController() override;
 
   // ImageDecodeController overrides.
@@ -177,6 +177,7 @@ class CC_EXPORT SoftwareImageDecodeController
     void AddUsage(size_t usage);
     void SubtractUsage(size_t usage);
     void ResetUsage();
+    size_t total_limit_bytes() const { return limit_bytes_; }
 
    private:
     size_t GetCurrentUsageSafe() const;