weblayer: Save the stack of Tab destruction

And include the stack when on throwIfDestroyed failure to make the
message more useful.

Change-Id: I4a801d7208cb35c44bf6fbd6d58f3f424eaefd61
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2561038
Auto-Submit: Bo <boliu@chromium.org>
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#831047}

weblayer/public/java/org/chromium/weblayer/Tab.java

@@ -47,6 +47,8 @@ public class Tab {
     private static final Map<Integer, Tab> sTabMap = new HashMap<Integer, Tab>();
 
     private ITab mImpl;
+    // Remember the stack of Tab destruction.
+    private Throwable mDestroyStack;
     private final NavigationController mNavigationController;
     private final FindInPageController mFindInPageController;
     private final MediaCaptureController mMediaCaptureController;
@@ -117,7 +119,7 @@ public class Tab {
 
     private void throwIfDestroyed() {
         if (mImpl == null) {
-            throw new IllegalStateException("Tab can not be used once destroyed");
+            throw new IllegalStateException("Tab can not be used once destroyed", mDestroyStack);
         }
     }
 
@@ -831,6 +833,7 @@ public class Tab {
             if (getTabById(mId) == this) unregisterTab(this);
             mDestroyOnRemove = false;
             mImpl = null;
+            mDestroyStack = new RuntimeException("onRemovedFromBrowser");
         }
     }
 
@@ -903,6 +906,7 @@ public class Tab {
                 // Ensure that the app will fail fast if the embedder mistakenly tries to call back
                 // into the implementation via this Tab.
                 mImpl = null;
+                mDestroyStack = new RuntimeException("onTabDestroyed");
             } else {
                 // This Tab should not have been destroyed yet.
                 assert mImpl != null;