Mozart: Fix 0x0 crashes in example views.

examples/ui/png_viewer/png_viewer.cc

 // Copyright 2014 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 <string>
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "mojo/application/application_runner_chromium.h"
@@ skipping 31 matching lines @@
   void OnPropertiesChanged(
       uint32_t old_scene_version,
       mojo::ui::ViewPropertiesPtr old_properties) override {
     UpdateScene();
   }
 
   void UpdateScene() {
     if (!properties())
       return;
 
+    auto update = mojo::gfx::composition::SceneUpdate::New();
+
     const mojo::Size& size = *properties()->view_layout->size;
-    mojo::RectF bounds;
-    bounds.width = size.width;
-    bounds.height = size.height;
+    if (size.width > 0 && size.height > 0) {
+      mojo::RectF bounds;
+      bounds.width = size.width;
+      bounds.height = size.height;
 
-    auto update = mojo::gfx::composition::SceneUpdate::New();
-    mojo::gfx::composition::ResourcePtr content_resource =
-        ganesh_renderer()->DrawCanvas(
-            size,
-            base::Bind(&PNGView::DrawContent, base::Unretained(this), size));
-    DCHECK(content_resource);
-    update->resources.insert(kContentImageResourceId, content_resource.Pass());
+      mojo::gfx::composition::ResourcePtr content_resource =
+          ganesh_renderer()->DrawCanvas(
+              size,
+              base::Bind(&PNGView::DrawContent, base::Unretained(this), size));
+      DCHECK(content_resource);
+      update->resources.insert(kContentImageResourceId,
+                               content_resource.Pass());
 
-    auto root_node = mojo::gfx::composition::Node::New();
-    root_node->op = mojo::gfx::composition::NodeOp::New();
-    root_node->op->set_image(mojo::gfx::composition::ImageNodeOp::New());
-    root_node->op->get_image()->content_rect = bounds.Clone();
-    root_node->op->get_image()->image_resource_id = kContentImageResourceId;
-    update->nodes.insert(kRootNodeId, root_node.Pass());
+      auto root_node = mojo::gfx::composition::Node::New();
+      root_node->op = mojo::gfx::composition::NodeOp::New();
+      root_node->op->set_image(mojo::gfx::composition::ImageNodeOp::New());
+      root_node->op->get_image()->content_rect = bounds.Clone();
+      root_node->op->get_image()->image_resource_id = kContentImageResourceId;
+      update->nodes.insert(kRootNodeId, root_node.Pass());
+    } else {
+      auto root_node = mojo::gfx::composition::Node::New();
+      update->nodes.insert(kRootNodeId, root_node.Pass());
+    }
 
     scene()->Update(update.Pass());
 
     auto metadata = mojo::gfx::composition::SceneMetadata::New();
     metadata->version = scene_version();
     scene()->Publish(metadata.Pass());
   }
 
   void DrawContent(const mojo::Size& size, SkCanvas* canvas) {
     canvas->clear(SK_ColorBLACK);
@@ skipping 66 matching lines @@
  private:
   DISALLOW_COPY_AND_ASSIGN(PNGContentViewerApp);
 };
 
 }  // namespace examples
 
 MojoResult MojoMain(MojoHandle application_request) {
   mojo::ApplicationRunnerChromium runner(new examples::PNGContentViewerApp());
   return runner.Run(application_request);
 }