[Media Session] Avoid undefined behavior when scoring images

Given an image whose shortest dimension is zero,
|GetImageAspectRatioScore| would run into a division by zero, which
leads to undefined behavior.

This CL prevents that by returning early. We return zero because such
an image is not desirable, and should rank lower than images with
non-zero heights and widths.

Change-Id: I80f3b9b3d832d8363994c11bdd073af011b963ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2185835Reviewed-by: Becca Hughes <beccahughes@chromium.org>
Commit-Queue: Chege Gitau <dagitau@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#766475}

services/media_session/public/cpp/media_image_manager.cc

@@ -26,6 +26,9 @@ const double kXIconTypeScore = 0.4;
 const double kGIFTypeScore = 0.3;
 
 double GetImageAspectRatioScore(const gfx::Size& size) {
+  if (size.width() == 0 || size.height() == 0)
+    return 0;
+
   double long_edge = std::max(size.width(), size.height());
   double short_edge = std::min(size.width(), size.height());
   return short_edge / long_edge;

services/media_session/public/cpp/media_image_manager_unittest.cc

@@ -182,4 +182,26 @@ TEST_F(MediaImageManagerTest, MinAndIdealAndImageSizeAreSame) {
   EXPECT_TRUE(manager.SelectImage(images));
 }
 
+TEST_F(MediaImageManagerTest, PreferImagesWithNonZeroArea) {
+  std::vector<MediaImage> images;
+
+  MediaImage image1;
+  image1.sizes.push_back(gfx::Size(kMinSize, kMinSize));
+  images.push_back(image1);
+
+  MediaImage image2;
+  image2.sizes.push_back(gfx::Size(kIdealSize, 0));
+  images.push_back(image2);
+
+  MediaImage image3;
+  image3.sizes.push_back(gfx::Size(0, kIdealSize));
+  images.push_back(image3);
+
+  MediaImage image4;
+  image4.sizes.push_back(gfx::Size(0, 0));
+  images.push_back(image4);
+
+  EXPECT_EQ(image1, manager()->SelectImage(images));
+}
+
 }  // namespace media_session