webapps: add splashscreen for installed webapps

chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
index 3f6b891bee4cb8e5d2ae5bcf95e1221b9c40cb41..3973c756b6a573bf24d6b2168861491ca8ce52bd 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java
@@ -204,7 +204,7 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
         super.preInflationStartup();
         ApplicationInitialization.enableFullscreenFlags(
                 getResources(), this, getControlContainerHeightResource());
-        getWindow().setBackgroundDrawableResource(R.color.light_background_color);
+        getWindow().setBackgroundDrawableResource(getBackgroundDrawableResource());
     }
 
     @SuppressLint("NewApi")
@@ -831,6 +831,10 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
         return R.dimen.control_container_height;
     }
 
+    protected int getBackgroundDrawableResource() {
+        return R.color.light_background_color;
+    }
+
     @Override
     public final void onAccessibilityStateChanged(boolean enabled) {
         checkAccessibility();