ThinWebView: Fixed a crash

Bug: 1019148
Change-Id: Ia49f1ac8317e4270225017231179b41fa3436d17
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890495Reviewed-by: Min Qin <qinmin@chromium.org>
Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710880}

chrome/browser/android/thin_webview/internal/java/src/org/chromium/chrome/browser/thinwebview/internal/CompositorViewImpl.java

@@ -54,6 +54,7 @@ public class CompositorViewImpl implements CompositorView {
     public void destroy() {
         if (mNativeCompositorViewImpl != 0) {
             CompositorViewImplJni.get().destroy(mNativeCompositorViewImpl, CompositorViewImpl.this);
+            mNativeCompositorViewImpl = 0;
         }
     }
 

chrome/browser/android/thin_webview/internal/java/src/org/chromium/chrome/browser/thinwebview/internal/ThinWebViewImpl.java

@@ -24,7 +24,7 @@ import org.chromium.ui.base.WindowAndroid;
 @JNINamespace("thin_webview::android")
 public class ThinWebViewImpl extends FrameLayout implements ThinWebView {
     private final CompositorView mCompositorView;
-    private final long mNativeThinWebViewImpl;
+    private long mNativeThinWebViewImpl;
     private WebContents mWebContents;
     private View mContentView;
 
@@ -66,6 +66,7 @@ public class ThinWebViewImpl extends FrameLayout implements ThinWebView {
         mCompositorView.destroy();
         if (mNativeThinWebViewImpl != 0) {
             ThinWebViewImplJni.get().destroy(mNativeThinWebViewImpl, ThinWebViewImpl.this);
+            mNativeThinWebViewImpl = 0;
         }
     }