cc: fix nullptr deref in software renderer.

cc/output/software_renderer.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/output/software_renderer.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/output/compositor_frame.h"
@@ skipping 480 matching lines @@
       MathUtil::ScaleRectProportional(QuadVertexRect(), gfx::RectF(quad->rect),
                                       gfx::RectF(quad->visible_rect)));
   SkRect content_rect = SkRect::MakeWH(quad->rect.width(), quad->rect.height());
 
   const SkBitmap* content = lock.sk_bitmap();
 
   sk_sp<SkImage> filter_image;
   if (!quad->filters.IsEmpty()) {
     sk_sp<SkImageFilter> filter = RenderSurfaceFilters::BuildImageFilter(
         quad->filters, gfx::SizeF(content_texture->size()));
-    SkIRect result_rect;
-    // TODO(ajuma): Apply the filter in the same pass as the content where
-    // possible (e.g. when there's no origin offset). See crbug.com/308201.
-    filter_image = ApplyImageFilter(filter.get(), quad, *content, &result_rect);
-    if (filter_image) {
-      gfx::RectF rect = gfx::SkRectToRectF(SkRect::Make(result_rect));
-      dest_rect = dest_visible_rect =
-          gfx::RectFToSkRect(MathUtil::ScaleRectProportional(
-              QuadVertexRect(), gfx::RectF(quad->rect), rect));
-      content_rect = SkRect::MakeWH(result_rect.width(), result_rect.height());
+    if (filter) {
+      SkIRect result_rect;
+      // TODO(ajuma): Apply the filter in the same pass as the content where
+      // possible (e.g. when there's no origin offset). See crbug.com/308201.
+      filter_image =
+          ApplyImageFilter(filter.get(), quad, *content, &result_rect);
+      if (result_rect.isEmpty()) {
+        return;
+      }
+      if (filter_image) {
+        gfx::RectF rect = gfx::SkRectToRectF(SkRect::Make(result_rect));
+        dest_rect = dest_visible_rect =
+            gfx::RectFToSkRect(MathUtil::ScaleRectProportional(
+                QuadVertexRect(), gfx::RectF(quad->rect), rect));
+        content_rect =
+            SkRect::MakeWH(result_rect.width(), result_rect.height());
+      }
     }
   }
 
   SkMatrix content_mat;
   content_mat.setRectToRect(content_rect, dest_rect,
                             SkMatrix::kFill_ScaleToFit);
 
   sk_sp<SkShader> shader;
   if (!filter_image) {
     shader =
@@ skipping 135 matching lines @@
                              SkImageFilter::kForward_MapDirection);
     *auto_bounds = dst_rect;
   } else {
     dst_rect = to_filter.bounds();
   }
 
   SkImageInfo dst_info =
       SkImageInfo::MakeN32Premul(dst_rect.width(), dst_rect.height());
   sk_sp<SkSurface> surface = SkSurface::MakeRaster(dst_info);
 
+  if (!surface) {
+    return nullptr;
+  }
+
   SkPaint paint;
   paint.setImageFilter(filter->makeWithLocalMatrix(local_matrix));
   surface->getCanvas()->translate(-dst_rect.x(), -dst_rect.y());
   surface->getCanvas()->drawBitmap(to_filter, quad->rect.x(), quad->rect.y(),
                                    &paint);
 
   return surface->makeImageSnapshot();
 }
 
 SkBitmap SoftwareRenderer::GetBackdropBitmap(
@@ skipping 60 matching lines @@
       ApplyImageFilter(filter.get(), quad, backdrop_bitmap, nullptr);
 
   if (!filter_backdrop_image)
     return nullptr;
 
   return filter_backdrop_image->makeShader(content_tile_mode, content_tile_mode,
                                            &filter_backdrop_transform);
 }
 
 }  // namespace cc