Initial ResizeObserver implementation

third_party/WebKit/LayoutTests/resize-observer/resources/resizeTestHelper.js

Index: third_party/WebKit/LayoutTests/resize-observer/resources/resizeTestHelper.js
diff --git a/third_party/WebKit/LayoutTests/resize-observer/resources/resizeTestHelper.js b/third_party/WebKit/LayoutTests/resize-observer/resources/resizeTestHelper.js
new file mode 100644
index 0000000000000000000000000000000000000000..83b21ad86fc084d9c2084cd8f6e39ad43545588d
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/resize-observer/resources/resizeTestHelper.js
@@ -0,0 +1,90 @@
+'use strict';
+
+/**
+ ResizeTestHelper is a framework to test ResizeObserver
+ notifications. Use it to make assertions about ResizeObserverEntries.
+
+ It handles timeouts, and queueing of multiple steps in a test.
+
+*/
+function ResizeTestHelper() {
+  this._pendingTests = [];
+  this._observer = new ResizeObserver(this._handleNotification.bind(this));
+}
+
+ResizeTestHelper.prototype = {
+
+  TIMEOUT: 2000,
+
+  // @return ResizeObserver
+  get observer() {
+    return this._observer;
+  },
+
+  _handleNotification: function(entries) {
+    if (this._currentTest) {
+      // console.log("notification");
+      let current = this._currentTest;
+      delete this._currentTest;
+      window.clearTimeout(current.timeoutId);
+      current.test.step(_ => {
+        // console.log("step");
+        let caughtEx = false;
+        try {
+          current.completion(entries);
+          current.test.done();
+        }
+        catch(ex) {
+          caughtEx = ex;
+        }
+        this.startTests();
+        if (caughtEx)
+          throw caughtEx;
+      });
+    }
+  },
+  _handleTimeout: function() {
+    if (this._currentTest) {
+      let current  = this._currentTest;
+      delete this._currentTest;
+      if (current.timeout) { // timeout is not an error
+        current.timeout();
+        current.test.done();
+        this.startTests();
+      }
+      else {
+        current.test.step(_ => {
+          assert_unreached("Timed out waiting for notification. (" + this.TIMEOUT + "ms)");
+          current.test.done();
+          this.startTests();
+        });
+      }
+    }
+  },
+
+  /*
+  Kicks off tests. Processes all the tests in order, until
+  _pendingTests is empty
+  */
+  startTests: function() {
+    if (this._currentTest) // only one test at a time
+      return;
+    if (this._pendingTests.length > 0) {
+      this._currentTest = this._pendingTests.shift();
+      this._currentTest.setup();
+      this._currentTest.timeoutId = this._currentTest.test.step_timeout(this._handleTimeout.bind(this), this.TIMEOUT);
+    }
+  },
+
+  /**
+  Adds new test to _pendingTests.
+   */
+  createTest: function(name, setup, completion, timeoutCb) {
+    this._pendingTests.push( {
+      test: async_test(name),
+      setup: setup,
+      completion: completion,
+      timeout: timeoutCb });
+  }
+
+}