Properly initialize WebStates in unit tests

Those tests trigger code path that access the toolbar if there
is an active WebState in the WebStateList. This requires that
the WebState returns non-null BrowserState and NavigationManager
so set the corresponding property on the TestWebState.

Bug: none
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Ic950a706b31ac153cdfb71b510681c09886c3da0
Reviewed-on: https://chromium-review.googlesource.com/1106176Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569228}

ios/chrome/browser/ui/location_bar/location_bar_coordinator_unittest.mm

@@ -78,6 +78,7 @@ class LocationBarLegacyCoordinatorTest : public PlatformTest {
     browser_state_ = test_cbs_builder.Build();
 
     auto web_state = std::make_unique<web::TestWebState>();
+    web_state->SetBrowserState(browser_state_.get());
     web_state->SetCurrentURL(GURL("http://test/"));
     web_state_list_.InsertWebState(0, std::move(web_state),
                                    WebStateList::INSERT_FORCE_INDEX,

ios/chrome/browser/ui/toolbar/clean/toolbar_mediator_unittest.mm

@@ -112,6 +112,7 @@ class ToolbarMediatorTest : public PlatformTest {
         std::make_unique<ToolbarTestNavigationManager>();
     navigation_manager_ = navigation_manager.get();
     test_web_state_ = std::make_unique<ToolbarTestWebState>();
+    test_web_state_->SetBrowserState(chrome_browser_state_.get());
     test_web_state_->SetNavigationManager(std::move(navigation_manager));
     test_web_state_->SetLoading(true);
     web_state_ = test_web_state_.get();
@@ -148,6 +149,9 @@ class ToolbarMediatorTest : public PlatformTest {
 
   void InsertNewWebState(int index) {
     auto web_state = std::make_unique<web::TestWebState>();
+    web_state->SetBrowserState(chrome_browser_state_.get());
+    web_state->SetNavigationManager(
+        std::make_unique<web::TestNavigationManager>());
     GURL url("http://test/" + std::to_string(index));
     web_state->SetCurrentURL(url);
     web_state_list_->InsertWebState(index, std::move(web_state),