Add BlimpView to a Chrome tab when Blimp is enabled.

ui/android/java/src/org/chromium/ui/base/WindowAndroid.java

Index: ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
diff --git a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
index cceb825154168f1b0c5147f5071e051f52999781..dabb468983aa8e19a23b3e5ce859786048a0485c 100644
--- a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
+++ b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
@@ -182,6 +182,11 @@ public class WindowAndroid {
         return new WindowAndroid(context);
     }
 
+    @CalledByNative
+    private void clearNativePointer() {
+        mNativeWindowAndroid = 0;
+    }
+
     /**
      * Set the delegate that will handle android permissions requests.
      */
@@ -502,8 +507,8 @@ public class WindowAndroid {
      */
     public void destroy() {
         if (mNativeWindowAndroid != 0) {
+            // Native code clears |mNativeWindowAndroid|.
             nativeDestroy(mNativeWindowAndroid);
-            mNativeWindowAndroid = 0;
         }
 
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {