Trying to be consistent when members are allowed to be NULL

Got a few crashes running the fuzzer locally, all related to handling NULL members/parameters in an inconsistent way.

BUG=skia:

Review URL: https://codereview.chromium.org/675013003

3 files changed, 14 insertions, 11 deletions

diff --git a/src/core/SkLocalMatrixShader.cpp b/src/core/SkLocalMatrixShader.cpp
index 62840dd3af..a7d2c15b0c 100644
--- a/src/core/SkLocalMatrixShader.cpp
+++ b/src/core/SkLocalMatrixShader.cpp
@@ -60,6 +60,10 @@ void SkLocalMatrixShader::toString(SkString* str) const {
 #endif
 
 SkShader* SkShader::CreateLocalMatrixShader(SkShader* proxy, const SkMatrix& localMatrix) {
+    if (NULL == proxy) {
+        return NULL;
+    }
+
     if (localMatrix.isIdentity()) {
         return SkRef(proxy);
     }
diff --git a/src/effects/SkColorFilterImageFilter.cpp b/src/effects/SkColorFilterImageFilter.cpp
index 2a8df5c672..806dd5dd01 100755
--- a/src/effects/SkColorFilterImageFilter.cpp
+++ b/src/effects/SkColorFilterImageFilter.cpp
@@ -60,6 +60,9 @@ bool matrix_needs_clamping(SkScalar matrix[20]) {
 SkColorFilterImageFilter* SkColorFilterImageFilter::Create(SkColorFilter* cf,
         SkImageFilter* input, const CropRect* cropRect, uint32_t uniqueID) {
     SkASSERT(cf);
+    if (NULL == cf) {
+        return NULL;
+    }
     SkScalar colorMatrix[20], inputMatrix[20];
     SkColorFilter* inputColorFilter;
     if (input && cf->asColorMatrix(colorMatrix)
@@ -78,9 +81,7 @@ SkColorFilterImageFilter* SkColorFilterImageFilter::Create(SkColorFilter* cf,
 
 SkColorFilterImageFilter::SkColorFilterImageFilter(SkColorFilter* cf,
         SkImageFilter* input, const CropRect* cropRect, uint32_t uniqueID)
-    : INHERITED(1, &input, cropRect, uniqueID), fColorFilter(cf) {
-    SkASSERT(cf);
-    SkSafeRef(cf);
+    : INHERITED(1, &input, cropRect, uniqueID), fColorFilter(SkRef(cf)) {
 }
 
 #ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
@@ -102,7 +103,7 @@ void SkColorFilterImageFilter::flatten(SkWriteBuffer& buffer) const {
 }
 
 SkColorFilterImageFilter::~SkColorFilterImageFilter() {
-    SkSafeUnref(fColorFilter);
+    fColorFilter->unref();
 }
 
 bool SkColorFilterImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& source,
diff --git a/src/effects/SkRectShaderImageFilter.cpp b/src/effects/SkRectShaderImageFilter.cpp
index fb34ed0007..09417c8840 100644
--- a/src/effects/SkRectShaderImageFilter.cpp
+++ b/src/effects/SkRectShaderImageFilter.cpp
@@ -20,20 +20,18 @@ SkRectShaderImageFilter* SkRectShaderImageFilter::Create(SkShader* s, const SkRe
         flags = 0x0;
     }
     CropRect cropRect(rect, flags);
-    return SkNEW_ARGS(SkRectShaderImageFilter, (s, &cropRect));
+    return s ? SkNEW_ARGS(SkRectShaderImageFilter, (s, &cropRect)) : NULL;
 }
 
 SkRectShaderImageFilter* SkRectShaderImageFilter::Create(SkShader* s, const CropRect* cropRect, uint32_t uniqueID) {
     SkASSERT(s);
-    return SkNEW_ARGS(SkRectShaderImageFilter, (s, cropRect, uniqueID));
+    return s ? SkNEW_ARGS(SkRectShaderImageFilter, (s, cropRect, uniqueID)) : NULL;
 }
 
 SkRectShaderImageFilter::SkRectShaderImageFilter(SkShader* s, const CropRect* cropRect,
                                                  uint32_t uniqueID)
   : INHERITED(0, NULL, cropRect, uniqueID)
-  , fShader(s) {
-    SkASSERT(s);
-    s->ref();
+  , fShader(SkRef(s)) {
 }
 
 #ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
@@ -55,7 +53,7 @@ void SkRectShaderImageFilter::flatten(SkWriteBuffer& buffer) const {
 }
 
 SkRectShaderImageFilter::~SkRectShaderImageFilter() {
-    SkSafeUnref(fShader);
+    fShader->unref();
 }
 
 bool SkRectShaderImageFilter::onFilterImage(Proxy* proxy,
@@ -78,7 +76,7 @@ bool SkRectShaderImageFilter::onFilterImage(Proxy* proxy,
     SkPaint paint;
     SkMatrix matrix(ctx.ctm());
     matrix.postTranslate(SkIntToScalar(-bounds.left()), SkIntToScalar(-bounds.top()));
-    paint.setShader(SkShader::CreateLocalMatrixShader(fShader, matrix))->unref();
+    SkSafeUnref(paint.setShader(SkShader::CreateLocalMatrixShader(fShader, matrix)));
 
     SkRect rect = SkRect::MakeWH(SkIntToScalar(bounds.width()), SkIntToScalar(bounds.height()));
     canvas.drawRect(rect, paint);