fix blank space on link preview when no site name (#2193)

app/components/post_attachment_opengraph/__snapshots__/post_attachment_opengraph.test.js.snap

@@ -76,6 +76,59 @@ exports[`PostAttachmentOpenGraph should match snapshot, without image and descri
 </Component>
 `;
 
+exports[`PostAttachmentOpenGraph should match snapshot, without site_name 1`] = `
+<Component
+  style={
+    Object {
+      "borderColor": "rgba(61,60,64,0.2)",
+      "borderRadius": 3,
+      "borderWidth": 1,
+      "flex": 1,
+      "marginTop": 10,
+      "padding": 10,
+    }
+  }
+>
+  <Component
+    style={
+      Object {
+        "flex": 1,
+        "flexDirection": "row",
+      }
+    }
+  >
+    <TouchableOpacity
+      activeOpacity={0.2}
+      onPress={[Function]}
+      style={
+        Object {
+          "flex": 1,
+        }
+      }
+    >
+      <Component
+        ellipsizeMode="tail"
+        numberOfLines={3}
+        style={
+          Array [
+            Object {
+              "color": "#2389d7",
+              "fontSize": 14,
+              "marginBottom": 10,
+            },
+            Object {
+              "marginRight": 0,
+            },
+          ]
+        }
+      >
+        Title
+      </Component>
+    </TouchableOpacity>
+  </Component>
+</Component>
+`;
+
 exports[`PostAttachmentOpenGraph should match state and snapshot, on renderDescription 1`] = `null`;
 
 exports[`PostAttachmentOpenGraph should match state and snapshot, on renderDescription 2`] = `

app/components/post_attachment_opengraph/post_attachment_opengraph.js

@@ -234,8 +234,9 @@ export default class PostAttachmentOpenGraph extends PureComponent {
 
         const style = getStyleSheet(theme);
 
-        return (
-            <View style={style.container}>
+        let siteTitle;
+        if (openGraphData.site_name) {
+            siteTitle = (
                 <View style={style.flex}>
                     <Text
                         style={style.siteTitle}
@@ -245,6 +246,12 @@ export default class PostAttachmentOpenGraph extends PureComponent {
                         {openGraphData.site_name}
                     </Text>
                 </View>
+            );
+        }
+
+        return (
+            <View style={style.container}>
+                {siteTitle}
                 <View style={style.wrapper}>
                     <TouchableOpacity
                         style={style.flex}

app/components/post_attachment_opengraph/post_attachment_opengraph.test.js

@@ -44,6 +44,20 @@ describe('PostAttachmentOpenGraph', () => {
         expect(wrapper.find(TouchableOpacity).exists()).toEqual(true);
     });
 
+    test('should match snapshot, without site_name', () => {
+        const newOpenGraphData = {
+            title: 'Title',
+            url: 'https://mattermost.com/',
+        };
+        const wrapper = shallow(
+            <PostAttachmentOpenGraph
+                {...baseProps}
+                openGraphData={newOpenGraphData}
+            />
+        );
+        expect(wrapper.getElement()).toMatchSnapshot();
+    });
+
     test('should match state and snapshot, on renderImage', () => {
         const wrapper = shallow(
             <PostAttachmentOpenGraph {...baseProps}/>