Added WasShown/WasHidden WebState and WebStateObserver API.

WebState's WasShown/WasHidden is called from Tab, so WebStateObserver
callbacks are actually work.
WebStateObserver's WasShown/WasHidden callbacks will allow to move
code from Tab to TabHelpers.

Bug: 616244
Change-Id: I2d8f3eb0f5854dd7204b9aec6db2aac593309638
Reviewed-on: https://chromium-review.googlesource.com/596783Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491739}

ios/chrome/browser/tabs/tab.mm

@@ -1794,14 +1794,16 @@ void TabInfoBarObserver::OnInfoBarReplaced(infobars::InfoBar* old_infobar,
 - (void)wasShown {
   _visible = YES;
   [self updateFullscreenWithToolbarVisible:YES];
-  [self.webController wasShown];
+  if (self.webState)
+    self.webState->WasShown();
   [_inputAccessoryViewController wasShown];
 }
 
 - (void)wasHidden {
   _visible = NO;
   [self updateFullscreenWithToolbarVisible:YES];
-  [self.webController wasHidden];
+  if (self.webState)
+    self.webState->WasHidden();
   [_inputAccessoryViewController wasHidden];
 }
 

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

@@ -33,6 +33,8 @@ class TestWebState : public WebState {
   bool ShouldSuppressDialogs() const override;
   void SetShouldSuppressDialogs(bool should_suppress) override;
   UIView* GetView() override;
+  void WasShown() override;
+  void WasHidden() override;
   BrowserState* GetBrowserState() const override;
   void OpenURL(const OpenURLParams& params) override {}
   void Stop() override {}

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

@@ -69,6 +69,16 @@ UIView* TestWebState::GetView() {
   return view_;
 }
 
+void TestWebState::WasShown() {
+  for (auto& observer : observers_)
+    observer.WasShown();
+}
+
+void TestWebState::WasHidden() {
+  for (auto& observer : observers_)
+    observer.WasHidden();
+}
+
 const NavigationManager* TestWebState::GetNavigationManager() const {
   return navigation_manager_.get();
 }

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

@@ -19,6 +19,10 @@ class TestWebStateObserver : public WebStateObserver {
   TestWebStateObserver(WebState* web_state);
   ~TestWebStateObserver() override;
 
+  // Arguments passed to |WasShown|.
+  web::TestWasShownInfo* was_shown_info() { return was_shown_info_.get(); }
+  // Arguments passed to |WasHidden|.
+  web::TestWasHiddenInfo* was_hidden_info() { return was_hidden_info_.get(); }
   // Arguments passed to |DidStartNavigation|.
   web::TestDidStartNavigationInfo* did_start_navigation_info() {
     return did_start_navigation_info_.get();
@@ -94,6 +98,8 @@ class TestWebStateObserver : public WebStateObserver {
 
  private:
   // WebStateObserver implementation:
+  void WasShown() override;
+  void WasHidden() override;
   void NavigationItemCommitted(const LoadCommittedDetails&) override;
   void PageLoaded(PageLoadCompletionStatus load_completion_status) override;
   void InterstitialDismissed() override;
@@ -118,6 +124,8 @@ class TestWebStateObserver : public WebStateObserver {
   void DidStartLoading() override;
   void DidStopLoading() override;
 
+  std::unique_ptr<web::TestWasShownInfo> was_shown_info_;
+  std::unique_ptr<web::TestWasHiddenInfo> was_hidden_info_;
   std::unique_ptr<web::TestCommitNavigationInfo> commit_navigation_info_;
   std::unique_ptr<web::TestLoadPageInfo> load_page_info_;
   std::unique_ptr<web::TestDismissInterstitialInfo> dismiss_interstitial_info_;

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

@@ -21,6 +21,16 @@ TestWebStateObserver::TestWebStateObserver(WebState* web_state)
     : WebStateObserver(web_state) {}
 TestWebStateObserver::~TestWebStateObserver() = default;
 
+void TestWebStateObserver::WasShown() {
+  was_shown_info_ = base::MakeUnique<web::TestWasShownInfo>();
+  was_shown_info_->web_state = web_state();
+}
+
+void TestWebStateObserver::WasHidden() {
+  was_hidden_info_ = base::MakeUnique<web::TestWasHiddenInfo>();
+  was_hidden_info_->web_state = web_state();
+}
+
 void TestWebStateObserver::NavigationItemCommitted(
     const LoadCommittedDetails& load_details) {
   commit_navigation_info_ = base::MakeUnique<web::TestCommitNavigationInfo>();

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

@@ -16,6 +16,16 @@ namespace web {
 class NavigationContext;
 class WebState;
 
+// Arguments passed to |WasShown|.
+struct TestWasShownInfo {
+  WebState* web_state;
+};
+
+// Arguments passed to |WasHidden|.
+struct TestWasHiddenInfo {
+  WebState* web_state;
+};
+
 // Arguments passed to |DidStartNavigation|.
 struct TestDidStartNavigationInfo {
   TestDidStartNavigationInfo();

ios/web/public/web_state/web_state.h

@@ -124,6 +124,10 @@ class WebState : public base::SupportsUserData {
   // caller to size the view.
   virtual UIView* GetView() = 0;
 
+  // Must be called when the WebState becomes shown/hidden.
+  virtual void WasShown() = 0;
+  virtual void WasHidden() = 0;
+
   // Gets the BrowserState associated with this WebState. Can never return null.
   virtual BrowserState* GetBrowserState() const = 0;
 

ios/web/public/web_state/web_state_observer.h

@@ -30,6 +30,10 @@ class WebStateObserver {
   // Returns the web state associated with this observer.
   WebState* web_state() const { return web_state_; }
 
+  // These methods are invoked every time the WebState changes visibility.
+  virtual void WasShown() {}
+  virtual void WasHidden() {}
+
   // This method is invoked when committed navigation items have been pruned.
   virtual void NavigationItemsPruned(size_t pruned_item_count) {}
 

ios/web/web_state/web_state_impl.h

@@ -175,6 +175,8 @@ class WebStateImpl : public WebState, public NavigationManagerDelegate {
   bool ShouldSuppressDialogs() const override;
   void SetShouldSuppressDialogs(bool should_suppress) override;
   UIView* GetView() override;
+  void WasShown() override;
+  void WasHidden() override;
   BrowserState* GetBrowserState() const override;
   void OpenURL(const WebState::OpenURLParams& params) override;
   void Stop() override;

ios/web/web_state/web_state_impl.mm

@@ -576,6 +576,18 @@ UIView* WebStateImpl::GetView() {
   return [web_controller_ view];
 }
 
+void WebStateImpl::WasShown() {
+  [web_controller_ wasShown];
+  for (auto& observer : observers_)
+    observer.WasShown();
+}
+
+void WebStateImpl::WasHidden() {
+  [web_controller_ wasHidden];
+  for (auto& observer : observers_)
+    observer.WasHidden();
+}
+
 BrowserState* WebStateImpl::GetBrowserState() const {
   return navigation_manager_->GetBrowserState();
 }

ios/web/web_state/web_state_impl_unittest.mm

@@ -267,6 +267,18 @@ TEST_F(WebStateImplTest, ObserverTest) {
       new TestWebStateObserver(web_state_.get()));
   EXPECT_EQ(web_state_.get(), observer->web_state());
 
+  // Test that WasShown() is called.
+  ASSERT_FALSE(observer->was_shown_info());
+  web_state_->WasShown();
+  ASSERT_TRUE(observer->was_shown_info());
+  EXPECT_EQ(web_state_.get(), observer->was_shown_info()->web_state);
+
+  // Test that WasHidden() is called.
+  ASSERT_FALSE(observer->was_hidden_info());
+  web_state_->WasHidden();
+  ASSERT_TRUE(observer->was_hidden_info());
+  EXPECT_EQ(web_state_.get(), observer->was_hidden_info()->web_state);
+
   // Test that LoadProgressChanged() is called.
   ASSERT_FALSE(observer->change_loading_progress_info());
   const double kTestLoadProgress = 0.75;