Add unit tests to text context

src/gpu/GrTextContext.cpp

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrTextContext.h"
 #include "GrContext.h"
 #include "GrDrawTarget.h"
@@ skipping 48 matching lines @@
     do {
         if (textContext->canDraw(rt, clip, paint, skPaint, viewMatrix)) {
             textContext->onDrawText(rt, clip, paint, skPaint, viewMatrix, text, byteLength, x, y,
                                     clipBounds);
             return;
         }
         textContext = textContext->fFallbackTextContext;
     } while (textContext);
 
     // fall back to drawing as a path
+    SkASSERT(fGpuDevice);
     this->drawTextAsPath(skPaint, viewMatrix, text, byteLength, x, y, clipBounds);
 }
 
 void GrTextContext::drawPosText(GrRenderTarget* rt, const GrClip& clip, const GrPaint& paint,
                                 const SkPaint& skPaint, const SkMatrix& viewMatrix,
                                 const char text[], size_t byteLength,
                                 const SkScalar pos[], int scalarsPerPosition,
                                 const SkPoint& offset, const SkIRect& clipBounds) {
     if (!fContext->getTextTarget()) {
         return;
     }
 
     GrTextContext* textContext = this;
     do {
         if (textContext->canDraw(rt, clip, paint, skPaint, viewMatrix)) {
             textContext->onDrawPosText(rt, clip, paint, skPaint, viewMatrix, text, byteLength, pos,
                                        scalarsPerPosition, offset, clipBounds);
             return;
         }
         textContext = textContext->fFallbackTextContext;
     } while (textContext);
 
     // fall back to drawing as a path
+    SkASSERT(fGpuDevice);
     this->drawPosTextAsPath(skPaint, viewMatrix, text, byteLength, pos, scalarsPerPosition, offset,
                             clipBounds);
 }
 
 void GrTextContext::drawTextBlob(GrRenderTarget* rt, const GrClip& clip, const SkPaint& skPaint,
                                  const SkMatrix& viewMatrix, const SkTextBlob* blob,
                                  SkScalar x, SkScalar y,
                                  SkDrawFilter* drawFilter, const SkIRect& clipBounds) {
     SkPaint runPaint = skPaint;
 
@@ skipping 147 matching lines @@
     if (cache->getAuxProcData(GlyphCacheAuxProc, &auxData)) {
         scaler = (GrFontScaler*)auxData;
     }
     if (NULL == scaler) {
         scaler = SkNEW_ARGS(GrFontScaler, (cache));
         cache->setAuxProc(GlyphCacheAuxProc, scaler);
     }
 
     return scaler;
 }