[Android WebAPK] Do not crash on empty share intent

This CL fixes a java.lang.StringIndexOutOfBoundsException in
HostBrowserLauncherParams#createWebShareTargetUriString() when the WebAPK receives the following
share intent:

Intent intent = new Intent(Intent.ACTION_SEND);
intent.setTyle("text/plain");

BUG=None
TEST=HostBrowserLauncherParamsTest.*

Change-Id: If14cafcb43ed3f7668a7165e071674027713316d
Reviewed-on: https://chromium-review.googlesource.com/c/1285069
Commit-Queue: Ethan Xu <xuethan@google.com>
Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
Reviewed-by: Glenn Hartmann <hartmanng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600956}

chrome/android/webapk/shell_apk/junit/src/org/chromium/webapk/shell_apk/HostBrowserLauncherParamsTest.java

@@ -66,6 +66,34 @@ public class HostBrowserLauncherParamsTest {
         Assert.assertEquals("https://www.chromium.org/wst?hello=world", uri);
     }
 
+    /*
+     * Test that {@link HostBrowserLauncherParams#createWebShareTargetUriString()} can handle
+     * the case where both values in every pair are null.
+     */
+    @Test
+    public void testCreateWebShareTargetUriStringAllNull() {
+        ArrayList<Pair<String, String>> params = new ArrayList<>();
+        params.add(new Pair<>(null, null));
+        params.add(new Pair<>(null, null));
+        String uri = HostBrowserLauncherParams.createWebShareTargetUriString(
+                "https://www.chromium.org/wst", params);
+        Assert.assertEquals("https://www.chromium.org/wst", uri);
+    }
+
+    /*
+     * Test that {@link HostBrowserLauncherParams#createWebShareTargetUriString()} can handle
+     * the cases where some keys in all pair are null.
+     */
+    @Test
+    public void testCreateWebShareTargetUriStringAllNullWithSomeElementNotNull() {
+        ArrayList<Pair<String, String>> params = new ArrayList<>();
+        params.add(new Pair<>("a", null));
+        params.add(new Pair<>(null, "b"));
+        String uri = HostBrowserLauncherParams.createWebShareTargetUriString(
+                "https://www.chromium.org/wst", params);
+        Assert.assertEquals("https://www.chromium.org/wst", uri);
+    }
+
     /*
      * Test that {@link HostBrowserLauncherParams#createWebShareTargetUriString()} handles replacing
      * the query string of an action url with an existing query.

chrome/android/webapk/shell_apk/src/org/chromium/webapk/shell_apk/HostBrowserLauncherParams.java

@@ -128,7 +128,11 @@ public class HostBrowserLauncherParams {
         Uri shareUri = Uri.parse(action);
         Uri.Builder builder = shareUri.buildUpon();
         // Uri.Builder uses %20 rather than + for spaces, the spec requires +.
-        builder.encodedQuery(queryBuilder.build().toString().replace("%20", "+").substring(1));
+        String queryString = queryBuilder.build().toString();
+        if (TextUtils.isEmpty(queryString)) {
+            return action;
+        }
+        builder.encodedQuery(queryString.replace("%20", "+").substring(1));
         return builder.build().toString();
     }