Bug 1690845. Don't ask Windows for the icon of an empty file extension because it returns the c: drive icon, which is not what we want. r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D105736

image/decoders/icon/win/nsIconChannel.cpp

@@ -503,6 +503,12 @@ nsresult nsIconChannel::GetHIconFromFile(bool aNonBlocking, HICON* hIcon) {
     filePath = u"."_ns + NS_ConvertUTF8toUTF16(defFileExt);
   }
 
+  if (!localFile && !fileExists &&
+      ((filePath.Length() == 1 && filePath.Last() == '.') ||
+       filePath.Length() == 0)) {
+    filePath = u".MozBogusExtensionMoz"_ns;
+  }
+
   if (aNonBlocking) {
     RefPtr<nsIEventTarget> target = DecodePool::Singleton()->GetIOEventTarget();
     RefPtr<IconAsyncOpenTask> task = new IconAsyncOpenTask(

image/test/reftest/generic/moz-icon-blank-1-almostref.html

@@ -0,0 +1,2 @@
+<!-- this should draw an icon similar to a blank document but with writing on it -->
+<img src="moz-icon://.txt?size=16">

image/test/reftest/generic/moz-icon-blank-1-antiref.html

@@ -0,0 +1,2 @@
+<!-- this draws the icon for current directory on the c: drive on windows -->
+<img src="moz-icon:file:///C:/?size=16">

image/test/reftest/generic/moz-icon-blank-1-antiref2.html

@@ -0,0 +1,2 @@
+<!-- this draws the icon for the c: drive on windows -->
+<img src="moz-icon:file:///C://?size=16">

image/test/reftest/generic/moz-icon-blank-1-ref.html

@@ -0,0 +1,2 @@
+<!-- this should draw a blank document icon -->
+<img src="moz-icon://bogus-unrecognized-icon.bogusunknown845?size=16">

image/test/reftest/generic/moz-icon-blank-1.html

@@ -0,0 +1,2 @@
+<!-- this should draw a blank document icon -->
+<img src="moz-icon://test?size=16&contentType=application/octet-stream">

image/test/reftest/generic/reftest.list

@@ -1,2 +1,6 @@
 HTTP == accept-image-catchall.html accept-image-catchall-ref.html
 skip-if(Android) != moz-icon-1.html about:blank
+== moz-icon-blank-1.html moz-icon-blank-1-ref.html
+skip-if(Android) != moz-icon-blank-1-ref.html moz-icon-blank-1-antiref.html
+skip-if(Android) != moz-icon-blank-1-ref.html moz-icon-blank-1-antiref2.html
+fuzzy-if(OSX,44-44,335-335) fuzzy-if(winWidget,64-78,45-68) == moz-icon-blank-1-almostref.html moz-icon-blank-1-ref.html