lacros: Provide default LacrosInitParams when running tests

browser_tests disable all crosapi calls and do not call
LacrosChromeService::Init(). LacrosChromeServiceImpl::init_params_ is
therefore "null". However, because LacrosInitParams is a small mojo
struct, it is an InlinedStructPtr, and init_params_.get() returns
a non-null pointer. This means existing code in lacros can call
LacrosChromeServiceImpl::init_params() and get a non-null value.

A later CL increases the size of LacrosInitParams, so it cannot be
inlined. This causes browser_tests failures because init_params()
starts returning null.

We want some value for InitParams in tests. Therefore create a
default-constructed version in tests.

Bug: none
Change-Id: I3ee0b15a276d0f04fc024ba3fbd7d2d1a892a72b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2463568
Commit-Queue: James Cook <jamescook@chromium.org>
Commit-Queue: Erik Chen <erikchen@chromium.org>
Auto-Submit: James Cook <jamescook@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815711}

chromeos/lacros/lacros_chrome_service_impl.cc

@@ -197,6 +197,12 @@ LacrosChromeServiceImpl::LacrosChromeServiceImpl(
     std::unique_ptr<LacrosChromeServiceDelegate> delegate)
     : delegate_(std::move(delegate)),
       sequenced_state_(nullptr, base::OnTaskRunnerDeleter(nullptr)) {
+  if (g_disable_all_crosapi_for_tests) {
+    // Tests don't call LacrosChromeService::Init(), so provide LacrosInitParams
+    // with default values.
+    init_params_ = crosapi::mojom::LacrosInitParams::New();
+  }
+
   // The sequence on which this object was constructed, and thus affine to.
   scoped_refptr<base::SequencedTaskRunner> affine_sequence =
       base::SequencedTaskRunnerHandle::Get();
@@ -316,6 +322,7 @@ void LacrosChromeServiceImpl::BindReceiver(
   }
 }
 
+// static
 void LacrosChromeServiceImpl::DisableCrosapiForTests() {
   g_disable_all_crosapi_for_tests = true;
 }