Make SkSmallAllocator obey the RAII invariants and be expandable

src/core/SkBlitter.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBlitter.h"
 #include "SkAntiRun.h"
 #include "SkColor.h"
@@ skipping 878 matching lines @@
     /*
      *  We create a SkShader::Context object, and store it on the blitter.
      */
     SkShader::Context* shaderContext = nullptr;
     if (shader) {
         const SkShader::ContextRec rec(*paint, matrix, nullptr,
                                        PreferredShaderDest(device.info()));
         size_t contextSize = shader->contextSize(rec);
         if (contextSize) {
             // Try to create the ShaderContext
-            void* storage = allocator->reserveT<SkShader::Context>(contextSize);
-            shaderContext = shader->createContext(rec, storage);
+            shaderContext = allocator->createWithIniterT<SkShader::Context>(
+                contextSize,
+                [&rec, shader](void* storage) {
+                    return shader->createContext(rec, storage);
+                });
             if (!shaderContext) {
-                allocator->freeLast();
                 return allocator->createT<SkNullBlitter>();
             }
             SkASSERT(shaderContext);
-            SkASSERT((void*) shaderContext == storage);
         } else {
             return allocator->createT<SkNullBlitter>();
         }
     }
 
     SkBlitter*  blitter = nullptr;
     switch (device.colorType()) {
         case kAlpha_8_SkColorType:
             if (drawCoverage) {
                 SkASSERT(nullptr == shader);
@@ skipping 97 matching lines @@
     fShaderContext->~Context();
     SkShader::Context* ctx = fShader->createContext(rec, (void*)fShaderContext);
     if (nullptr == ctx) {
         // Need a valid context in fShaderContext's storage, so we can later (or our caller) call
         // the in-place destructor.
         new (fShaderContext) SkZeroShaderContext(*fShader, rec);
         return false;
     }
     return true;
 }