Enable gfx::Image to be created from empty platform images.

ui/gfx/image/image_unittest.cc

 // Copyright (c) 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 "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/image/image_unittest_util.h"
 
 #if defined(TOOLKIT_GTK)
@@ skipping 29 matching lines @@
 
   // Test calling SwapRepresentations() with an empty image.
   gfx::Image image2(gt::CreateBitmap(25, 25));
   EXPECT_FALSE(image2.IsEmpty());
 
   image.SwapRepresentations(&image2);
   EXPECT_FALSE(image.IsEmpty());
   EXPECT_TRUE(image2.IsEmpty());
 }
 
+// Test constructing a gfx::Image from an empty PlatformImage.
+TEST_F(ImageTest, EmptyImageFromEmptyPlatformImage) {
+#if defined(OS_MACOSX) || defined(TOOLKIT_GTK)
+  gfx::Image image1(NULL);
+  EXPECT_TRUE(image1.IsEmpty());
+  EXPECT_EQ(0U, image1.RepresentationCount());
+#endif
+
+  // SkBitmap and gfx::ImageSkia are available on all platforms.
+  SkBitmap bitmap;
+  EXPECT_TRUE(bitmap.empty());
+  gfx::Image image2(bitmap);
+  EXPECT_TRUE(image2.IsEmpty());
+  EXPECT_EQ(0U, image2.RepresentationCount());
+
+  gfx::ImageSkia image_skia;
+  EXPECT_TRUE(image_skia.isNull());
+  gfx::Image image3(image_skia);
+  EXPECT_TRUE(image3.IsEmpty());
+  EXPECT_EQ(0U, image3.RepresentationCount());
+}
+
 TEST_F(ImageTest, SkiaToSkia) {
   gfx::Image image(gt::CreateBitmap(25, 25));
   const SkBitmap* bitmap = image.ToSkBitmap();
   EXPECT_TRUE(bitmap);
   EXPECT_FALSE(bitmap->isNull());
   EXPECT_EQ(1U, image.RepresentationCount());
 
   // Make sure double conversion doesn't happen.
   bitmap = image.ToSkBitmap();
   EXPECT_TRUE(bitmap);
@@ skipping 316 matching lines @@
     image = gfx::Image(gfx::ImageSkiaRep(bitmap, ui::SCALE_FACTOR_100P));
   }
   EXPECT_TRUE(!image.ToSkBitmap()->isNull());
 }
 
 // Integration tests with UI toolkit frameworks require linking against the
 // Views library and cannot be here (ui_unittests doesn't include it). They
 // instead live in /chrome/browser/ui/tests/ui_gfx_image_unittest.cc.
 
 }  // namespace