Google Docs accessibility (#1875)

* Add accessibility option for forcing Google Docs HTML-based rendering

* Update settings

* Send a documentStart message at document start

* Add accessibility script for Google Docs

* Set up accessibility

* Update tests

4 files changed, 93 insertions, 2 deletions

diff --git a/ext/js/accessibility/google-docs.js b/ext/js/accessibility/google-docs.js
new file mode 100644
index 00000000..f9ba0f7f
--- /dev/null
+++ b/ext/js/accessibility/google-docs.js
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2021  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+(() => {
+    let parent = document.head;
+    if (parent === null) {
+        parent = document.documentElement;
+        if (parent === null) { return; }
+    }
+    const script = document.createElement('script');
+    script.textContent = 'window._docs_force_html_by_ext = true;';
+    parent.appendChild(script);
+})();
diff --git a/ext/js/background/backend.js b/ext/js/background/backend.js
index 623f3612..b4b9bc27 100644
--- a/ext/js/background/backend.js
+++ b/ext/js/background/backend.js
@@ -124,7 +124,8 @@ class Backend {
             ['isTabSearchPopup',             {async: true,  contentScript: true,  handler: this._onApiIsTabSearchPopup.bind(this)}],
             ['triggerDatabaseUpdated',       {async: false, contentScript: true,  handler: this._onApiTriggerDatabaseUpdated.bind(this)}],
             ['testMecab',                    {async: true,  contentScript: true,  handler: this._onApiTestMecab.bind(this)}],
-            ['textHasJapaneseCharacters',    {async: false, contentScript: true,  handler: this._onApiTextHasJapaneseCharacters.bind(this)}]
+            ['textHasJapaneseCharacters',    {async: false, contentScript: true,  handler: this._onApiTextHasJapaneseCharacters.bind(this)}],
+            ['documentStart',                {async: false, contentScript: true,  handler: this._onDocumentStart.bind(this)}]
         ]);
         this._messageHandlersWithProgress = new Map([
         ]);
@@ -745,6 +746,12 @@ class Backend {
         return this._japaneseUtil.isStringPartiallyJapanese(text);
     }
 
+    _onDocumentStart(params, sender) {
+        const {tab, frameId, url} = sender;
+        if (typeof url !== 'string' || typeof tab !== 'object' || tab === null) { return; }
+        this._updateTabAccessibility(url, tab, frameId);
+    }
+
     // Command handlers
 
     async _onCommandOpenSearchPage(params) {
@@ -2207,4 +2214,31 @@ class Backend {
             // NOP
         }
     }
+
+    _updateTabAccessibility(url, tab, frameId) {
+        let file = null;
+
+        switch (new URL(url).hostname) {
+            case 'docs.google.com':
+                {
+                    const optionsContext = {depth: 0, url};
+                    const options = this._getProfileOptions(optionsContext);
+                    if (!options.accessibility.forceGoogleDocsHtmlRendering) { return; }
+                    file = 'js/accessibility/google-docs.js';
+                }
+                break;
+        }
+
+        if (file === null) { return; }
+
+        const details = {
+            allFrames: false,
+            frameId,
+            file,
+            matchAboutBlank: true,
+            runAt: 'document_start'
+        };
+        const callback = () => this._checkLastError(chrome.runtime.lastError);
+        chrome.tabs.executeScript(tab.id, details, callback);
+    }
 }
diff --git a/ext/js/data/options-util.js b/ext/js/data/options-util.js
index 42d8a93a..30ffadb1 100644
--- a/ext/js/data/options-util.js
+++ b/ext/js/data/options-util.js
@@ -462,7 +462,8 @@ class OptionsUtil {
             {async: true,  update: this._updateVersion10.bind(this)},
             {async: false, update: this._updateVersion11.bind(this)},
             {async: true,  update: this._updateVersion12.bind(this)},
-            {async: true,  update: this._updateVersion13.bind(this)}
+            {async: true,  update: this._updateVersion13.bind(this)},
+            {async: false, update: this._updateVersion14.bind(this)}
         ];
         if (typeof targetVersion === 'number' && targetVersion < result.length) {
             result.splice(targetVersion);
@@ -864,4 +865,15 @@ class OptionsUtil {
         }
         return options;
     }
+
+    _updateVersion14(options) {
+        // Version 14 changes:
+        //  Added accessibility options.
+        for (const profile of options.profiles) {
+            profile.options.accessibility = {
+                forceGoogleDocsHtmlRendering: false
+            };
+        }
+        return options;
+    }
 }
diff --git a/ext/js/document-start.js b/ext/js/document-start.js
new file mode 100644
index 00000000..de1c2403
--- /dev/null
+++ b/ext/js/document-start.js
@@ -0,0 +1,18 @@
+/*
+ * Copyright (C) 2021  Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+chrome.runtime.sendMessage({action: 'documentStart'}, () => void chrome.runtime.lastError);