ViewHierarchyExceptionHandler calls View methods on non-UI thread

[agrieve]

This stack comes up in failing chrome tests from time to time:

C 11:28:54.816   87.729s Main  java.lang.AssertionError: Class was initialized on the UI thread, but current operation was performed on a background thread: Thread[Instr: org.chromium.base.test.BaseChromiumAndroidJUnitRunner,5,main]
C 11:28:54.816   87.730s Main  	at org.chromium.base.ThreadUtils$ThreadChecker.assertOnValidThreadHelper(ThreadUtils.java:97)
C 11:28:54.816   87.730s Main  	at org.chromium.base.ThreadUtils$ThreadChecker.assertOnValidThread(ThreadUtils.java:71)
C 11:28:54.816   87.730s Main  	at org.chromium.base.UserDataHost.checkThreadAndState(UserDataHost.java:64)
C 11:28:54.816   87.730s Main  	at org.chromium.base.UserDataHost.getUserData(UserDataHost.java:96)
C 11:28:54.816   87.730s Main  	at org.chromium.content.browser.webcontents.WebContentsImpl.getOrSetUserData(WebContentsImpl.java:1042)
C 11:28:54.816   87.730s Main  	at org.chromium.content.browser.input.ImeAdapterImpl.fromWebContents(ImeAdapterImpl.java:253)
C 11:28:54.816   87.730s Main  	at org.chromium.content_public.browser.ImeAdapter.fromWebContents(ImeAdapter.java:32)
C 11:28:54.816   87.730s Main  	at org.chromium.components.embedder_support.view.ContentView.onCreateInputConnection(ContentView.java:360)
C 11:28:54.816   87.730s Main  	at androidx.test.espresso.util.HumanReadables.describe(HumanReadables.java:247)
C 11:28:54.816   87.730s Main  	at androidx.test.espresso.util.HumanReadables.getViewHierarchyErrorMessage(HumanReadables.java:116)
C 11:28:54.816   87.730s Main  	at androidx.test.espresso.util.HumanReadables.getViewHierarchyErrorMessage(HumanReadables.java:73)
C 11:28:54.816   87.730s Main  	at androidx.test.espresso.base.ViewHierarchyExceptionHandler.dumpFullViewHierarchyToFile(ViewHierarchyExceptionHandler.java:96)
C 11:28:54.816   87.730s Main  	at androidx.test.espresso.base.ViewHierarchyExceptionHandler.handleSafely(ViewHierarchyExceptionHandler.java:65)
C 11:28:54.816   87.730s Main  	at androidx.test.espresso.base.ViewHierarchyExceptionHandler.handleSafely(ViewHierarchyExceptionHandler.java:38)
C 11:28:54.816   87.730s Main  	at androidx.test.espresso.base.DefaultFailureHandler$TypedFailureHandler.handle(DefaultFailureHandler.java:158)
C 11:28:54.816   87.730s Main  	at androidx.test.espresso.base.DefaultFailureHandler.handle(DefaultFailureHandler.java:120)
C 11:28:54.816   87.730s Main  	at androidx.test.espresso.ViewInteraction.waitForAndHandleInteractionResults(ViewInteraction.java:385)
C 11:28:54.816   87.730s Main  	at androidx.test.espresso.ViewInteraction.check(ViewInteraction.java:366)
C 11:28:54.816   87.730s Main  	at org.chromium.chrome.browser.tasks.tab_management.ArchivedTabsDialogCoordinatorTest.testContentDescription(ArchivedTabsDialogCoordinatorTest.java:754)

Espresso normally jumps to the UI thread to interact with Views, but I think that got missed for ViewHierarchyExceptionHandler. It should do a thread hop before accessing Views.

[agrieve]

Note: adding a thread hop to fix the above exception just leads to another one:

C 13:11:43.055   48.889s Main  	at org.chromium.base.ThreadUtils$ThreadChecker.assertOnValidThreadHelper(ThreadUtils.java:97)
C 13:11:43.055   48.889s Main  	at org.chromium.base.ThreadUtils$ThreadChecker.assertOnValidThread(ThreadUtils.java:71)
C 13:11:43.055   48.889s Main  	at org.chromium.base.UserDataHost.checkThreadAndState(UserDataHost.java:64)
C 13:11:43.055   48.889s Main  	at org.chromium.base.UserDataHost.getUserData(UserDataHost.java:96)
C 13:11:43.055   48.889s Main  	at org.chromium.content.browser.webcontents.WebContentsImpl.getOrSetUserData(WebContentsImpl.java:1042)
C 13:11:43.055   48.889s Main  	at org.chromium.content.browser.input.ImeAdapterImpl.fromWebContents(ImeAdapterImpl.java:253)
C 13:11:43.055   48.889s Main  	at org.chromium.content_public.browser.ImeAdapter.fromWebContents(ImeAdapter.java:32)
C 13:11:43.055   48.889s Main  	at org.chromium.components.embedder_support.view.ContentView.onCreateInputConnection(ContentView.java:360)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.util.HumanReadables.describe(HumanReadables.java:247)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.util.HumanReadables.getViewHierarchyErrorMessage(HumanReadables.java:116)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.NoMatchingViewException.getErrorMessage(NoMatchingViewException.java:88)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.NoMatchingViewException.<init>(NoMatchingViewException.java:53)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.NoMatchingViewException.<init>(Unknown Source:0)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.NoMatchingViewException$Builder.build(NoMatchingViewException.java:185)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.base.DefaultFailureHandler.lambda$getNoMatchingViewExceptionTruncater$0(DefaultFailureHandler.java:93)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.base.DefaultFailureHandler$$ExternalSyntheticLambda1.truncateExceptionMessage(D8$$SyntheticClass:0)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.base.ViewHierarchyExceptionHandler.handleSafely(ViewHierarchyExceptionHandler.java:75)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.base.ViewHierarchyExceptionHandler.handleSafely(ViewHierarchyExceptionHandler.java:41)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.base.DefaultFailureHandler$TypedFailureHandler.handle(DefaultFailureHandler.java:158)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.base.DefaultFailureHandler.handle(DefaultFailureHandler.java:120)
C 13:11:43.055   48.889s Main  	at androidx.test.espresso.ViewInteraction.waitForAndHandleInteractionResults(ViewInteraction.java:385)
C 13:11:43.055   48.890s Main  	at androidx.test.espresso.ViewInteraction.check(ViewInteraction.java:366)

This also shows that HumanReadables.getViewHierarchyErrorMessage() is called twice for the same exception, which maybe is a thing to fix as well.

[agrieve]

This patch fixes things locally in Chrome:

19a20
> import android.os.Looper;
31a33,34
> import java.util.concurrent.atomic.AtomicReference;
> import java.util.function.Supplier;
72c75
<     Throwable error = truncater.truncateExceptionMessage(exception, msgLen, viewHierarchyFile);
---
>     Throwable error = runOnUiThread(exception, () -> truncater.truncateExceptionMessage(exception, msgLen, viewHierarchyFile));
92a96,119
>   private static <T> T runOnUiThread(RootViewException e, Supplier<T> func) {
>     if (Looper.myLooper() == Looper.getMainLooper()) {
>       return func.get();
>     }
>
>     AtomicReference<T> ret = new AtomicReference<>();
>     e.getRootView().post(() -> {
>       ret.set(func.get());
>       synchronized (ret) {
>         ret.notifyAll();
>       }
>     });
>     synchronized (ret) {
>       while (ret.get() == null) {
>         try {
>           ret.wait();
>         } catch (InterruptedException unused) {
>           // Ignore.
>         }
>       }
>     }
>     return ret.get();
>   }
>
95c122
<     String viewHierarchyMsg =
---
>     String viewHierarchyMsg = runOnUiThread(error, () ->
100c127
<             /* problemViewSuffix= */ null);
---
>             /* problemViewSuffix= */ null));

Probably a "proper" fix would use dagger to inject the @MainThread Executor, but since I just patched the one file in a chromium checkout, I don't have the ability to run the dagger annotation processor in order to play around with that.

Also not sure how to best go about not dumping the view hierarchy twice...