Add js injection receiver methods to test web state.

Bug: 
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Ia5890c49825428177dbdc4c2a9429616bb92d747
Reviewed-on: https://chromium-review.googlesource.com/744521Reviewed-by: Eugene But <eugenebut@chromium.org>
Reviewed-by: Mike Dougherty <michaeldo@chromium.org>
Reviewed-by: Hiroshi Ichikawa <ichikawa@chromium.org>
Commit-Queue: John Wu <jzw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512852}

ios/web/public/test/fakes/test_web_state.h

@@ -87,6 +87,7 @@ class TestWebState : public WebState {
 
   // Setters for test data.
   void SetBrowserState(BrowserState* browser_state);
+  void SetJSInjectionReceiver(CRWJSInjectionReceiver* injection_receiver);
   void SetContentIsHTML(bool content_is_html);
   void SetLoading(bool is_loading);
   void SetCurrentURL(const GURL& url);
@@ -109,6 +110,7 @@ class TestWebState : public WebState {
 
  private:
   BrowserState* browser_state_;
+  CRWJSInjectionReceiver* injection_receiver_;
   bool web_usage_enabled_;
   bool is_loading_;
   bool is_visible_;

ios/web/public/test/fakes/test_web_state.mm

@@ -128,7 +128,7 @@ void TestWebState::SetIsEvicted(bool value) {
 }
 
 CRWJSInjectionReceiver* TestWebState::GetJSInjectionReceiver() const {
-  return nullptr;
+  return injection_receiver_;
 }
 
 void TestWebState::ExecuteJavaScript(const base::string16& javascript) {}
@@ -173,6 +173,11 @@ void TestWebState::SetBrowserState(BrowserState* browser_state) {
   browser_state_ = browser_state;
 }
 
+void TestWebState::SetJSInjectionReceiver(
+    CRWJSInjectionReceiver* injection_receiver) {
+  injection_receiver_ = injection_receiver;
+}
+
 void TestWebState::SetContentIsHTML(bool content_is_html) {
   content_is_html_ = content_is_html;
 }