Skip reporting ANR on zero pid process

Though currently the only case is from broadcast timeout
on a process forking by unresponsive webview_zygote, skip
the case to avoid noise reports.

Bug: 227349843
Test: AnrHelperTest
Change-Id: I433c4d33e14619bec764b99a1334ebe7c6137bb0

services/core/java/com/android/server/am/AnrHelper.java

@@ -79,6 +79,11 @@ class AnrHelper {
             WindowProcessController parentProcess, boolean aboveSystem, String annotation) {
         final int incomingPid = anrProcess.mPid;
         synchronized (mAnrRecords) {
+            if (incomingPid == 0) {
+                // Extreme corner case such as zygote is no response to return pid for the process.
+                Slog.i(TAG, "Skip zero pid ANR, process=" + anrProcess.processName);
+                return;
+            }
             if (mProcessingPid == incomingPid) {
                 Slog.i(TAG, "Skip duplicated ANR, pid=" + incomingPid + " " + annotation);
                 return;

services/tests/servicestests/src/com/android/server/am/AnrHelperTest.java

@@ -70,6 +70,7 @@ public class AnrHelperTest {
         final Context context = getInstrumentation().getTargetContext();
         runWithDexmakerShareClassLoader(() -> {
             mAnrApp = mock(ProcessRecord.class);
+            mAnrApp.mPid = 12345;
             final ProcessErrorStateRecord errorState = mock(ProcessErrorStateRecord.class);
             setFieldValue(ProcessErrorStateRecord.class, errorState, "mProcLock",
                     new ActivityManagerProcLock());
@@ -130,7 +131,6 @@ public class AnrHelperTest {
         }).when(mAnrApp.mErrorState).appNotResponding(anyString(), any(), any(), any(),
                 anyBoolean(), anyString(), anyBoolean());
         final ApplicationInfo appInfo = new ApplicationInfo();
-        mAnrApp.mPid = 12345;
         final Runnable reportAnr = () -> mAnrHelper.appNotResponding(mAnrApp,
                 "activityShortComponentName", appInfo, "parentShortComponentName",
                 null /* parentProcess */, false /* aboveSystem */, "annotation");