Handle OffscreenCanvas.convertToBlob exceptions: EncodingError & InvalidStateError

third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-convertToBlob-exceptions.html

Index: third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-convertToBlob-exceptions.html
diff --git a/third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-convertToBlob-exceptions.html b/third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-convertToBlob-exceptions.html
index 03629b8f99d39c96c9f2cf9826200c3438b9fed4..8ce169d935994bff0289b639a026f3bd8d582c45 100644
--- a/third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-convertToBlob-exceptions.html
+++ b/third_party/WebKit/LayoutTests/fast/canvas/OffscreenCanvas-convertToBlob-exceptions.html
@@ -33,7 +33,29 @@ async_test(function(t) {
         assert_true(e instanceof DOMException);
         assert_equals(e.name, "IndexSizeError");
     }));
-}, "Test that call convertToBlob on a OffscreenCanvas with size 0 throws exception");
+}, "Test that call convertToBlob on an OffscreenCanvas with size 0 throws exception");
+
+async_test(function(t) {
+    var webp_max_dimension = 16383; // Based on WEBPImageEncoder.cpp?l=52
+    var offscreenCanvas = new OffscreenCanvas(10, webp_max_dimension + 1);
+    var ctx = offscreenCanvas.getContext("2d");
+    offscreenCanvas.convertToBlob({type: "image/webp"}).then(t.step_func_done(function() {
+        assert_false("convertToBlob didn't throw, but should be");
+    }), t.step_func_done(function(e) {
+        assert_true(e instanceof DOMException);
+        assert_equals(e.name, "EncodingError");
+    }));
+}, "Test that call convertToBlob throws EncodingError exception when encoding fails");
+
+async_test(function(t) {
+    var offscreenCanvas = new OffscreenCanvas(10, 10);
+    offscreenCanvas.convertToBlob().then(t.step_func_done(function() {
+        assert_false("convertToBlob didn't throw, but should be");
+    }), t.step_func_done(function(e) {
+        assert_true(e instanceof DOMException);
+        assert_equals(e.name, "InvalidStateError");
+    }));
+}, "Test that call convertToBlob on an OffscreenCanvas without contexts throws exception");
 
 </script>