Check for destroyed WebView before adding a callback in didNavigateMainFrame

Check to make sure at the time that didNavigateMainFrame occurs that
the WebView is not destroyed (in which case skip registering the
visual state listener callback for onPageCommitVisible).

BUG=481534

Review URL: https://codereview.chromium.org/1109833002

Cr-Commit-Position: refs/heads/master@{#327062}

2 files changed, 16 insertions, 8 deletions

diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index 59ede16..0a0e853 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -2628,6 +2628,13 @@ public class AwContents implements SmartClipProvider,
         });
     }
 
+    protected void insertVisualStateCallbackIfNotDestroyed(
+            long requestId, VisualStateCallback callback) {
+        if (TRACE) Log.d(TAG, "insertVisualStateCallbackIfNotDestroyed");
+        if (isDestroyed()) return;
+        nativeInsertVisualStateCallback(mNativeAwContents, requestId, callback);
+    }
+
     // --------------------------------------------------------------------------------------------
     // This is the AwViewMethods implementation that does real work. The AwViewMethodsImpl is
     // hooked up to the WebView in embedded mode and to the FullScreenView in fullscreen mode,
diff --git a/android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java b/android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java
index de5dfb1..ec722f6 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwWebContentsObserver.java
@@ -68,14 +68,15 @@ public class AwWebContentsObserver extends WebContentsObserver {
                 public void run() {
                     AwContents awContents = mAwContents.get();
                     if (awContents != null) {
-                        awContents.insertVisualStateCallback(0, new VisualStateCallback() {
-                            @Override
-                            public void onComplete(long requestId) {
-                                AwContentsClient client = mAwContentsClient.get();
-                                if (client == null) return;
-                                client.onPageCommitVisible(url);
-                            }
-                        });
+                        awContents.insertVisualStateCallbackIfNotDestroyed(
+                                0, new VisualStateCallback() {
+                                    @Override
+                                    public void onComplete(long requestId) {
+                                        AwContentsClient client = mAwContentsClient.get();
+                                        if (client == null) return;
+                                        client.onPageCommitVisible(url);
+                                    }
+                                });
                     }
                 }
             });