Auto merge of #10100 - paulrouget:historyOnLocationChange, r=paulrouget

Add history information to mozbrowserlocationchange event

This is a change in the Browser API itself.

Before, on `mozbrowserlocationchange`, we would call `getCanGoBack()` and `getCanGoForward()`. Two asynchronous methods called on an event, which doesn't make much sense, especially because we already know on `mozbrowserlocationchange` if we can go back/forward. So here I'm adding 2 new properties to the event to tell if the iframe can go back/forward.

The way `event.detail` is defined also changed. Before, `event.detail` was a string (the new uri), now it's an object (`{uri:String,canGoBack:bool,canGoForward:bool}`).

This is one of the design flaw of the early Browser API: not using objects for the detail property, making it hard to extend the event payload.

So that makes this event not backward compatible. We can:
1. just don't care. It's up to the client to test if event.detail is a string or not if it needs to be compatible with Gecko
2. fix it in Gecko. The client will still have to test `event.detail` to make it compatible with older version of gecko
3. rename `mozbrowserlocationchange` to something else (`mozbrowserlocationchange2` ?)

Please advise.

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components/compositing/constellation.rs

@@ -1655,8 +1655,11 @@ impl<LTF: LayoutThreadFactory, STF: ScriptThreadFactory> Constellation<LTF, STF>
             // If this is an iframe, then send the event with new url
             if let Some((containing_pipeline_id, subpage_id, url)) = event_info {
                 let parent_pipeline = self.pipeline(containing_pipeline_id);
-                parent_pipeline.trigger_mozbrowser_event(subpage_id,
-                                                         MozBrowserEvent::LocationChange(url));
+                let frame_id = *self.pipeline_to_frame_map.get(&pipeline_id).unwrap();
+                let can_go_backward = !self.frame(frame_id).prev.is_empty();
+                let can_go_forward = !self.frame(frame_id).next.is_empty();
+                let event = MozBrowserEvent::LocationChange(url, can_go_backward, can_go_forward);
+                parent_pipeline.trigger_mozbrowser_event(subpage_id, event);
             }
         }
     }

components/script/dom/htmliframeelement.rs

@@ -6,6 +6,7 @@ use document_loader::{LoadType, LoadBlocker};
 use dom::attr::{Attr, AttrValue};
 use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::BrowserElementBinding::BrowserElementIconChangeEventDetail;
+use dom::bindings::codegen::Bindings::BrowserElementBinding::BrowserElementLocationChangeEventDetail;
 use dom::bindings::codegen::Bindings::BrowserElementBinding::BrowserElementSecurityChangeDetail;
 use dom::bindings::codegen::Bindings::BrowserElementBinding::BrowserShowModalPromptEventDetail;
 use dom::bindings::codegen::Bindings::HTMLIFrameElementBinding;
@@ -323,9 +324,16 @@ impl MozBrowserEventDetailBuilder for HTMLIFrameElement {
                     mixedState: None,
                 }.to_jsval(cx, rval);
             }
-            MozBrowserEvent::LocationChange(ref string) | MozBrowserEvent::TitleChange(ref string) => {
+            MozBrowserEvent::TitleChange(ref string) => {
                 string.to_jsval(cx, rval);
             }
+            MozBrowserEvent::LocationChange(uri, can_go_back, can_go_forward) => {
+                BrowserElementLocationChangeEventDetail {
+                    uri: Some(DOMString::from(uri)),
+                    canGoBack: Some(can_go_back),
+                    canGoForward: Some(can_go_forward),
+                }.to_jsval(cx, rval);
+            }
             MozBrowserEvent::IconChange(rel, href, sizes) => {
                 BrowserElementIconChangeEventDetail {
                     rel: Some(DOMString::from(rel)),

components/script/dom/webidls/BrowserElement.webidl

@@ -54,6 +54,12 @@ dictionary BrowserElementSecurityChangeDetail {
   boolean mixedContent;
 };
 
+dictionary BrowserElementLocationChangeEventDetail {
+  DOMString uri;
+  boolean canGoBack;
+  boolean canGoForward;
+};
+
 dictionary BrowserElementIconChangeEventDetail {
   DOMString rel;
   DOMString href;

components/script_traits/lib.rs

@@ -424,7 +424,7 @@ pub enum MozBrowserEvent {
     /// Sent when the browser `<iframe>` starts to load a new page.
     LoadStart,
     /// Sent when a browser `<iframe>`'s location changes.
-    LocationChange(String),
+    LocationChange(String, bool, bool),
     /// Sent when window.open() is called within a browser `<iframe>`.
     OpenWindow,
     /// Sent when the SSL state changes within a browser `<iframe>`.
@@ -451,7 +451,7 @@ impl MozBrowserEvent {
             MozBrowserEvent::IconChange(_, _, _) => "mozbrowsericonchange",
             MozBrowserEvent::LoadEnd => "mozbrowserloadend",
             MozBrowserEvent::LoadStart => "mozbrowserloadstart",
-            MozBrowserEvent::LocationChange(_) => "mozbrowserlocationchange",
+            MozBrowserEvent::LocationChange(_, _, _) => "mozbrowserlocationchange",
             MozBrowserEvent::OpenWindow => "mozbrowseropenwindow",
             MozBrowserEvent::SecurityChange(_) => "mozbrowsersecuritychange",
             MozBrowserEvent::ShowModalPrompt(_, _, _, _) => "mozbrowsershowmodalprompt",

tests/wpt/mozilla/meta/MANIFEST.json

@@ -6024,6 +6024,12 @@
             "url": "/_mozilla/mozilla/mozbrowser/mozbrowsericonchange_event.html"
           }
         ],
+        "mozilla/mozbrowser/mozbrowserlocationchange_event.html": [
+          {
+            "path": "mozilla/mozbrowser/mozbrowserlocationchange_event.html",
+            "url": "/_mozilla/mozilla/mozbrowser/mozbrowserlocationchange_event.html"
+          }
+        ],
         "mozilla/mozbrowser/mozbrowsersecuritychange_event.html": [
           {
             "path": "mozilla/mozbrowser/mozbrowsersecuritychange_event.html",

tests/wpt/mozilla/tests/mozilla/mozbrowser/iframe_goback.html

@@ -19,8 +19,8 @@
   iframe.src = url1;
 
   iframe.addEventListener("mozbrowserlocationchange", e => {
-    locations.push(e.detail);
-    if (e.detail == url2) {
+    locations.push(e.detail.uri);
+    if (e.detail.uri == url2) {
       iframe.goBack();
     }
     if (locations.length == expected_locations.length) {

tests/wpt/mozilla/tests/mozilla/mozbrowser/mozbrowserlocationchange_event.html

@@ -0,0 +1,59 @@
+<head>
+<title>Browser API; mozbrowserlocationchange event</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<script>
+
+async_test(function(t) {
+
+  var url1 = "data:,1";
+  var url2 = "data:,2";
+  var url3 = "data:,3";
+
+  var received_events = []
+  var expected_events = [
+    url1, false, false,
+    url2, true,  false,
+    url3, true,  false,
+    url2, true,  true,
+    url1, false, true,
+    url2, true,  true,
+    url3, true,  false,
+  ];
+
+  var iframe = document.createElement("iframe");
+  iframe.mozbrowser = "true";
+  iframe.src = url1;
+
+  var actions = [
+    function() {iframe.src = url2},
+    function() {iframe.src = url3},
+    function() {iframe.goBack()},
+    function() {iframe.goBack()},
+    function() {iframe.goForward()},
+    function() {iframe.goForward()},
+  ];
+
+  var action_idx = 0;
+
+  iframe.addEventListener("mozbrowserlocationchange", e => {
+    received_events.push(e.detail.uri);
+    received_events.push(e.detail.canGoBack);
+    received_events.push(e.detail.canGoForward);
+
+    if (action_idx < actions.length) {
+      actions[action_idx++]();
+    } else {
+       assert_array_equals(received_events, expected_events);
+       t.done();
+    }
+  });
+
+  document.body.appendChild(iframe);
+
+});
+
+</script>
+</body>

tests/wpt/mozilla/tests/mozilla/mozbrowser/redirect.html

@@ -10,7 +10,7 @@
         iframe.mozbrowser = "true";
         iframe.src = "redirect_init.html?pipe=status(302)|header(Location,redirect_final.html)";
         iframe.addEventListener("mozbrowserlocationchange", t.step_func(e => {
-            assert_equals(e.detail, new URL("redirect_final.html", location).href);
+            assert_equals(e.detail.uri, new URL("redirect_final.html", location).href);
             t.done();
         }));
         document.body.appendChild(iframe);