GWP-ASan: Work around WaitForMultiprocessTestChildExit bug

WaitForMultiprocessTestChildExit on Android currently can't handle child
process crashes due to threading requirements for the Android-specific
implementation. Hack around it for now.

Bug: 973167
Change-Id: I7027dba463150802516ea525f4fc4e2cdfd8d18a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1725335
Commit-Queue: Vlad Tsyrklevich <vtsyrklevich@chromium.org>
Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>
Auto-Submit: Vlad Tsyrklevich <vtsyrklevich@chromium.org>
Reviewed-by: Vitaly Buka <vitalybuka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682105}

components/gwp_asan/crash_handler/crash_handler_unittest.cc

@@ -223,12 +223,23 @@ class CrashHandlerTest : public base::MultiProcessTest,
     base::Process process =
         base::SpawnMultiProcessTestChild("CrashingProcess", cmd_line, options);
 
+#if !defined(OS_ANDROID)
     int exit_code = -1;
     EXPECT_TRUE(WaitForMultiprocessTestChildExit(
         process, TestTimeouts::action_max_timeout(), &exit_code));
     EXPECT_NE(exit_code, kSuccess);
-
     return (exit_code != kSuccess);
+#else
+    // TODO(https://crbug.com/976063): Android's implementation of
+    // WaitForMultiprocessTestChildExit can't detect child process crashes, this
+    // can be fixed after minSdkVersion >= Q.
+    for (int i = 0; i < TestTimeouts::action_max_timeout().InSeconds(); i++) {
+      if (kill(process.Pid(), 0) && errno == ESRCH)
+        return true;
+      sleep(1);
+    }
+    return false;
+#endif
   }
 
   // Given a directory with a single crashpad exception, read and parse the