Add desired width & height to drawContext (as opposed to using the width & height of the RT)

include/gpu/GrContext.h

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrContext_DEFINED
 #define GrContext_DEFINED
 
@@ skipping 166 matching lines @@
      *         rendering quality for the display. Alternatively returns 0 if
      *         MSAA is not supported or recommended to be used by default.
      */
     int getRecommendedSampleCount(GrPixelConfig config, SkScalar dpi) const;
 
     /**
      * Returns a helper object to orchestrate draws.
      * Callers assume the creation ref of the drawContext
      * NULL will be returned if the context has been abandoned.
      *
+     * @param  width        width of the portion of the rt that will actually be drawn to
+     * @param  height       height of the portion of the rt that will actually be drawn to
      * @param  rt           the render target receiving the draws
      * @param  surfaceProps the surface properties (mainly defines text drawing)
      *
      * @return a draw context
      */
-    sk_sp<GrDrawContext> drawContext(sk_sp<GrRenderTarget> rt, const SkSurfaceProps* = nullptr);
+    sk_sp<GrDrawContext> drawContext(int width, int height,
+                                     sk_sp<GrRenderTarget> rt,
+                                     const SkSurfaceProps* = nullptr);
 
     /**
      * Create both a GrRenderTarget and a matching GrDrawContext to wrap it.
      * We guarantee that "asTexture" will succeed for drawContexts created
      * via this entry point.
      */
     sk_sp<GrDrawContext> newDrawContext(SkBackingFit fit, 
                                         int width, int height,
                                         GrPixelConfig config,
                                         int sampleCnt = 0,
@@ skipping 291 matching lines @@
     SkAutoTUnref<const GrCaps>  fCaps;
     uint32_t                    fContextUniqueID;
 
     friend class GrContext;
     friend class SkImage;
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif