conversations: make message input and navbar bgs opaque

Change-Id: I88892014b8c6fb99b49dc7e6eac1314d1b02f124

ring-android/app/src/main/res/drawable/msg_input_bg.xml

+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <shape>
+            <gradient
+                android:angle="90"
+                android:startColor="@color/background"
+                android:centerColor="@color/background"
+                android:endColor="#00000000"
+                android:type="linear" />
+        </shape>
+    </item>
+</selector>
\ No newline at end of file

ring-android/app/src/main/res/layout/frag_conversation.xml

@@ -183,14 +183,23 @@
                 </LinearLayout>
             </androidx.cardview.widget.CardView>
 
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_alignParentBottom="true"
+                android:background="@drawable/msg_input_bg"
+                android:orientation="vertical"
+                android:visibility="visible"
+                tools:visibility="visible">
+
                 <androidx.cardview.widget.CardView
                     android:id="@+id/cvMessageInput"
                     android:layout_width="match_parent"
                     android:layout_height="wrap_content"
-                android:layout_alignParentBottom="true"
-                android:layout_marginLeft="8dp"
-                android:layout_marginRight="8dp"
-                android:layout_marginBottom="8dp"
+                    android:layout_marginTop="2dp"
+                    android:layout_marginRight="12dp"
+                    android:layout_marginBottom="12dp"
+                    android:layout_marginLeft="12dp"
                     android:visibility="gone"
                     app:cardCornerRadius="@dimen/conversation_message_input_radius"
                     app:cardElevation="4dp"
@@ -278,6 +287,7 @@
 
                     </LinearLayout>
                 </androidx.cardview.widget.CardView>
+            </LinearLayout>
         </RelativeLayout>
 
     </FrameLayout>

ring-android/app/src/main/res/values-v27/styles.xml

@@ -3,7 +3,7 @@
 
     <style name="AppThemeBase.Fullscreen" parent="AppThemeBase">
         <item name="android:windowDrawsSystemBarBackgrounds">true</item>
-        <item name="android:navigationBarColor">@color/transparent</item>
+        <item name="android:navigationBarColor">@color/background</item>
     </style>
 
     <style name="AppThemeBase.DarkToolbar" parent="AppThemeBase">

ring-android/app/src/main/res/values/styles.xml

@@ -60,7 +60,7 @@
 
     <!-- Conversation theme for older APIs -->
     <style name="AppThemeBase.Fullscreen" parent="AppThemeBase">
-        <item name="android:navigationBarColor">@color/transparent</item>
+        <item name="android:navigationBarColor">@color/background</item>
         <item name="android:windowTranslucentStatus">true</item>
         <item name="android:windowTranslucentNavigation">true</item>
     </style>