Beef up GrContext::AutoMatrix to handle doing GrPaint matrix adjustments.

R=robertphillips@google.com
Review URL: https://codereview.appspot.com/6656047

git-svn-id: http://skia.googlecode.com/svn/trunk@5918 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/SkMorphologyImageFilter.cpp b/src/effects/SkMorphologyImageFilter.cpp
index e00d94a..64d22be 100644
--- a/src/effects/SkMorphologyImageFilter.cpp
+++ b/src/effects/SkMorphologyImageFilter.cpp
@@ -442,14 +442,19 @@
                             SkISize radius) {
     GrContext* context = srcTexture->getContext();
     srcTexture->ref();
-    GrContext::AutoMatrix avm(context, GrMatrix::I());
+
+    GrContext::AutoMatrix am;
+    am.setIdentity(context);
+
     GrContext::AutoClip acs(context, GrRect::MakeWH(SkIntToScalar(srcTexture->width()),
                                                     SkIntToScalar(srcTexture->height())));
+
     GrTextureDesc desc;
     desc.fFlags = kRenderTarget_GrTextureFlagBit | kNoStencil_GrTextureFlagBit;
     desc.fWidth = SkScalarCeilToInt(rect.width());
     desc.fHeight = SkScalarCeilToInt(rect.height());
     desc.fConfig = kRGBA_8888_GrPixelConfig;
+
     if (radius.fWidth > 0) {
         GrAutoScratchTexture ast(context, desc);
         GrContext::AutoRenderTarget art(context, ast.texture()->asRenderTarget());