Mozart: Fix 0x0 crashes in example views.

examples/ui/pdf_viewer/pdf_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 <memory>
 #include <string>
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 151 matching lines @@
 
     callback.Run(false);
   }
 
   // |ChoreographerDelegate|:
   void OnDraw(const mojo::gfx::composition::FrameInfo& frame_info,
               const base::TimeDelta& time_delta) override {
     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(&PDFDocumentView::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(&PDFDocumentView::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->hit_test_behavior =
-        mojo::gfx::composition::HitTestBehavior::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->hit_test_behavior =
+          mojo::gfx::composition::HitTestBehavior::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) {
     if (!cached_image_) {
@@ skipping 93 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(PDFContentViewerApp);
 };
 
 }  // namespace examples
 
 MojoResult MojoMain(MojoHandle application_request) {
   mojo::ApplicationRunnerChromium runner(new examples::PDFContentViewerApp());
   return runner.Run(application_request);
 }