Refactor download image-MIME-type-detection code.

chrome/browser/download/download_item_model_unittest.cc

Index: chrome/browser/download/download_item_model_unittest.cc
diff --git a/chrome/browser/download/download_item_model_unittest.cc b/chrome/browser/download/download_item_model_unittest.cc
index dfb07feff443ef48d4b1f11afa0a28ef4cd563c8..6017a0db57c8d6948675a18d093847bbb79eb433 100644
--- a/chrome/browser/download/download_item_model_unittest.cc
+++ b/chrome/browser/download/download_item_model_unittest.cc
@@ -30,6 +30,7 @@ using safe_browsing::DownloadFileType;
 using ::testing::Mock;
 using ::testing::NiceMock;
 using ::testing::Return;
+using ::testing::ReturnRef;
 using ::testing::ReturnRefOfCopy;
 using ::testing::SetArgPointee;
 using ::testing::_;
@@ -382,6 +383,23 @@ TEST_F(DownloadItemModelTest, DangerLevel) {
   EXPECT_EQ(DownloadFileType::ALLOW_ON_USER_GESTURE, model().GetDangerLevel());
 }
 
+TEST_F(DownloadItemModelTest, HasSupportedImageMimeType) {
+  SetupDownloadItemDefaults();
+
+  // When the item has a supported image MIME type, true should be returned.
+  ON_CALL(item(), GetMimeType()).WillByDefault(Return("image/png"));
+  EXPECT_TRUE(model().HasSupportedImageMimeType());
+
+  // An unsupported MIME type should result in false being returned...
+  ON_CALL(item(), GetMimeType()).WillByDefault(Return("image/unsupported"));
+  EXPECT_FALSE(model().HasSupportedImageMimeType());
+
+  // ... unless the target path has a well-known image extension.
+  const base::FilePath kTargetPath(FILE_PATH_LITERAL("/foo/image.png"));
+  ON_CALL(item(), GetTargetFilePath()).WillByDefault(ReturnRef(kTargetPath));
+  EXPECT_TRUE(model().HasSupportedImageMimeType());

[svaldez, 2016/08/08 15:07:52]

Can you add a test for /foo/image.txt returning false, and "/foo/image." doing
the right thing. 

[Daniel Erat, 2016/08/08 16:02:14]

Done.

+}
+
 TEST_F(DownloadItemModelTest, ShouldRemoveFromShelfWhenComplete) {
   const struct TestCase {
     DownloadItem::DownloadState state;