AW: dismiss dialog when user presses cancel

Instead of finishing the Activity, this dismisses the dialog when the
user presses "cancel." This permits the user to see information about
other crashes, even if they don't want to upload them.

Bug: 1062500
Test: Manual
Change-Id: Iee6d8e159aa61e77b1de1c97c7621f69657e9f52
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2108165
Auto-Submit: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Hazem Ashmawy <hazems@chromium.org>
Commit-Queue: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#751405}

android_webview/nonembedded/java/src/org/chromium/android_webview/devui/CrashesListActivity.java

@@ -273,7 +273,7 @@ public class CrashesListActivity extends Activity {
                                         + " Do you want to proceed?")
                                 .setPositiveButton("Upload",
                                         (dialog, id) -> attemptUploadCrash(crashInfo.localId))
-                                .setNegativeButton("Cancel", (dialog, id) -> finish())
+                                .setNegativeButton("Cancel", (dialog, id) -> dialog.dismiss())
                                 .create()
                                 .show();
                     } else {