[Cleanup] Add an explicit threading assertion.

android_webview/java/src/org/chromium/android_webview/crash/MinidumpUploaderImpl.java

Index: android_webview/java/src/org/chromium/android_webview/crash/MinidumpUploaderImpl.java
diff --git a/android_webview/java/src/org/chromium/android_webview/crash/MinidumpUploaderImpl.java b/android_webview/java/src/org/chromium/android_webview/crash/MinidumpUploaderImpl.java
index 14227a5ec489dbb18d8ae6ca430dccac6796c31b..dfb917b861e47abde8874e54da7b4c4ffdcb6696 100644
--- a/android_webview/java/src/org/chromium/android_webview/crash/MinidumpUploaderImpl.java
+++ b/android_webview/java/src/org/chromium/android_webview/crash/MinidumpUploaderImpl.java
@@ -133,6 +133,7 @@ public class MinidumpUploaderImpl implements MinidumpUploader {
                 // Note that CommandLine/CommandLineUtil are not thread safe. They are initialized
                 // on the main thread, but before the current worker thread started - so this thread
                 // will have seen the initialization of the CommandLine.
+                ThreadUtils.assertOnUiThread();

[Tobias Sargeant, 2017/03/01 08:04:44]

This looks ok, but it's not consistent with the comment (which mentions "this
thread" in a way that says that it might be called on multiple threads). If the
commandline data structure is constant after initialization, do we need restrict
it to a single thread?

                 return CommandLine.getInstance().hasSwitch(
                         CommandLineUtil.CRASH_UPLOADS_ENABLED_FOR_TESTING_SWITCH);
             }