Fix flaky ChildProcessTest.ChildHasCleanExit test on Android

This change makes sure we save the clean exit value if the connection to
the child process is lost.

Bug: 911716
Change-Id: I9e0ac28e4ed18a3852fa157a4ce1295552d79bc4
Reviewed-on: https://chromium-review.googlesource.com/c/1370644Reviewed-by: Bo <boliu@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615968}

base/android/child_process_unittest.cc

@@ -22,8 +22,7 @@ MULTIPROCESS_TEST_MAIN(WaitingMain) {
 
 class ChildProcessTest : public MultiProcessTest {};
 
-// TODO(http://crbug.com/911716): Test has been flaky.
-TEST_F(ChildProcessTest, DISABLED_ChildHasCleanExit) {
+TEST_F(ChildProcessTest, ChildHasCleanExit) {
   Process process = SpawnChild("BasicMain");
   int exit_code = 0;
   EXPECT_TRUE(WaitForMultiprocessTestChildExit(

base/test/android/java/src/org/chromium/base/MultiprocessTestClientLauncher.java

@@ -43,6 +43,8 @@ public final class MultiprocessTestClientLauncher {
     private static final SparseArray<MultiprocessTestClientLauncher> sPidToLauncher =
             new SparseArray<>();
 
+    private static final SparseArray<Boolean> sPidToCleanExit = new SparseArray<>();
+
     private static final SparseArray<Integer> sPidToMainResult = new SparseArray<>();
 
     private static final Object sLauncherHandlerInitLock = new Object();
@@ -105,6 +107,7 @@ public final class MultiprocessTestClientLauncher {
                     assert isRunningOnLauncherThread();
                     assert sPidToLauncher.get(connection.getPid())
                             == MultiprocessTestClientLauncher.this;
+                    sPidToCleanExit.put(connection.getPid(), connection.hasCleanExit());
                     sPidToLauncher.remove(connection.getPid());
                 }
             };
@@ -336,7 +339,7 @@ public final class MultiprocessTestClientLauncher {
 
         MultiprocessTestClientLauncher launcher = sPidToLauncher.get(pid);
         if (launcher == null) {
-            return false;
+            return sPidToCleanExit.get(pid, false);
         }
         return launcher.mLauncher.getConnection().hasCleanExit();
     }