first cut at HQ GPU scaling; refactored existing bicubic scaler

include/core/SkError.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkError_DEFINED
 #define SkError_DEFINED
 
@@ skipping 29 matching lines @@
      *  everything, but perhaps a paint can get into a bad state somehow.
      */
     kInvalidPaint_SkError,
 
     /** Skia was unable to allocate memory to perform some task.
      */
     kOutOfMemory_SkError,
 
     /** Skia failed while trying to consume some external resource.
      */
-    kParseError_SkError
+    kParseError_SkError,
+    
+    /** Something went wrong internally; could be resource exhaustion but
+      * will often be a bug.
+     */
+    kInternalError_SkError
 };
 
 /** Return the current per-thread error code.  Error codes are "sticky"; they
  *  are not not reset by subsequent successful operations.
  */
 SkError SkGetLastError();
 
 /** Clear the current per-thread error code back to kNoError_SkError.
  */
 void SkClearLastError();
@@ skipping 16 matching lines @@
 void SkSetErrorCallback(SkErrorCallbackFunction cb, void *context);
 
 /** Get a human-readable description of the last (per-thread) error that
  *  occurred.  The returned error message will include not only a human
  *  readable version of the error code, but also information about the
  *  conditions that led to the error itself.
  */
 const char *SkGetLastErrorString();
 
 #endif /* SkError_DEFINED */