[ChromeDriver] XML special case in Get Element CSS Value

Bug: chromedriver:1994
Change-Id: Ic15edd6634d5a8cc118703a86155a90eda602a7d
Reviewed-on: https://chromium-review.googlesource.com/c/1292407Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Tatiana Buldina <buldina@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605490}

chrome/test/chromedriver/element_commands.cc

@@ -608,15 +608,24 @@ Status ExecuteGetElementValueOfCSSProperty(
                                       const std::string& element_id,
                                       const base::DictionaryValue& params,
                                       std::unique_ptr<base::Value>* value) {
+  bool is_xml = false;
+  Status status = IsDocumentTypeXml(session, web_view, &is_xml);
+  if (status.IsError())
+    return status;
+
+  if (is_xml) {
+      value->reset(new base::Value(""));
+  } else {
     std::string property_name;
     if (!params.GetString("propertyName", &property_name))
       return Status(kUnknownError, "missing 'propertyName'");
     std::string property_value;
-  Status status = GetElementEffectiveStyle(
+    status = GetElementEffectiveStyle(
         session, web_view, element_id, property_name, &property_value);
     if (status.IsError())
       return status;
     value->reset(new base::Value(property_value));
+  }
   return Status(kOk);
 }
 

chrome/test/chromedriver/element_util.cc

@@ -358,6 +358,25 @@ Status IsElementFocused(
   return Status(kOk);
 }
 
+Status IsDocumentTypeXml(
+    Session* session,
+    WebView* web_view,
+    bool* is_xml_document) {
+
+  std::unique_ptr<base::Value> contentType;
+  Status status = web_view->EvaluateScript(
+      session->GetCurrentFrameId(),
+      "document.contentType", &contentType);
+  if (status.IsError())
+          return status;
+  if (base::LowerCaseEqualsASCII(contentType->GetString(),
+                                 "text/xml"))
+    *is_xml_document = true;
+  else
+    *is_xml_document = false;
+  return Status(kOk);
+}
+
 Status GetElementAttribute(Session* session,
                            WebView* web_view,
                            const std::string& element_id,

chrome/test/chromedriver/element_util.h

@@ -45,6 +45,11 @@ Status IsElementFocused(
     const std::string& element_id,
     bool* is_focused);
 
+Status IsDocumentTypeXml(
+    Session* session,
+    WebView* web_view,
+    bool* is_xml_document);
+
 Status GetElementAttribute(Session* session,
                            WebView* web_view,
                            const std::string& element_id,