[MERGE][FIX] bus, mail, web: several cross-tab communication fixes

### [FIX] bus: background slave tabs should not loose notifications

Slave tabs missed some notifications in case the local storage
event's `newValue` did not match actual value in local storage. This
happens when master tab overwrites a value that slave tabs did not
take the time to read. Slave tabs should now always handle all local
storage events.

Task-ID 2044231

### [FIX] bus, mail: correctly synchronize document chat windows

Cross-tab synchronization of document chat windows resulted sometimes
with an infinite loop. This happens due to tabs relying on actual
value in the local storage and all document chat windows state being
set as a single local storage entry. Cross-tab communication of
document chat windows now is relying on event's `newValue`, and each
document chat window has its own local storage entry. Changes from
local storage no longer writes again in the local storage, so that
it no longer makes an echo (= infinite loop).

Task-Id 2034997

closes odoo/odoo#36177

Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

3 files changed, 31 insertions, 6 deletions

diff --git a/addons/web/static/src/js/core/abstract_storage_service.js b/addons/web/static/src/js/core/abstract_storage_service.js
index ef828b5dd5c..5d724f87911 100644
--- a/addons/web/static/src/js/core/abstract_storage_service.js
+++ b/addons/web/static/src/js/core/abstract_storage_service.js
@@ -45,6 +45,19 @@ var AbstractStorageService = AbstractService.extend({
         return val ? JSON.parse(val) : defaultValue;
     },
     /**
+     * @param {integer} index
+     * @return {string}
+     */
+    key: function (index) {
+        return this.storage.key(index);
+    },
+    /**
+     * @return {integer}
+     */
+    length: function () {
+        return this.storage.length;
+    },
+    /**
      * Removes the given key from the storage
      *
      * @param {string} key
diff --git a/addons/web/static/src/js/core/local_storage.js b/addons/web/static/src/js/core/local_storage.js
index 0ae98498b31..ecc0cb7b78f 100644
--- a/addons/web/static/src/js/core/local_storage.js
+++ b/addons/web/static/src/js/core/local_storage.js
@@ -35,12 +35,10 @@ try {
             var newValue = e.originalEvent.newValue;
             try {
                 JSON.parse(newValue);
-                if (localStorage.getItem(key) === newValue) {
-                    storage.trigger('storage', {
-                        key: key,
-                        newValue: newValue,
-                    });
-                }
+                storage.trigger('storage', {
+                    key: key,
+                    newValue: newValue,
+                });
             } catch (error) {}
         });
         return storage;
diff --git a/addons/web/static/src/js/core/ram_storage.js b/addons/web/static/src/js/core/ram_storage.js
index 9bf0fc29f93..abad86c4538 100644
--- a/addons/web/static/src/js/core/ram_storage.js
+++ b/addons/web/static/src/js/core/ram_storage.js
@@ -31,6 +31,7 @@ var RamStorage = Class.extend(mixins.EventDispatcherMixin, {
      */
     clear: function () {
         this.storage = Object.create(null);
+        this.length = 0;
     },
     /**
      * Returns the value associated with a given key in the storage
@@ -42,11 +43,21 @@ var RamStorage = Class.extend(mixins.EventDispatcherMixin, {
         return this.storage[key];
     },
     /**
+     * @param {integer} index
+     * @return {string}
+     */
+    key: function (index) {
+        return _.keys(this.storage)[index];
+    },
+    /**
      * Removes the given key from the storage
      *
      * @param {string} key
      */
     removeItem: function (key) {
+        if (key in this.storage) {
+            this.length--;
+        }
         delete this.storage[key];
         this.trigger('storage', {key: key, newValue: null});
     },
@@ -58,6 +69,9 @@ var RamStorage = Class.extend(mixins.EventDispatcherMixin, {
      * @param {string} value
      */
     setItem: function (key, value) {
+        if (!(key in this.storage)) {
+            this.length++;
+        }
         this.storage[key] = value;
         this.trigger('storage', {key: key, newValue: value});
     },