[iOS] Move content below header the first time a WebState is activated.

This CL also renames UpdateFullscreenWebViewProxyForReplacedScrollView()
to MoveContentBelowHeader(), as it is used in additional places other
than just for replaced scroll views.

Bug: 769379
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I330e20e33501429140a8ea3dfd9e8afa34d47fcf
Reviewed-on: https://chromium-review.googlesource.com/933921
Commit-Queue: Kurt Horimoto <kkhorimoto@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#538925}

ios/chrome/browser/ui/fullscreen/BUILD.gn

@@ -46,6 +46,8 @@ source_set("coordinators") {
 
 source_set("internal") {
   sources = [
+    "fullscreen_content_adjustment_util.h",
+    "fullscreen_content_adjustment_util.mm",
     "fullscreen_controller_factory.mm",
     "fullscreen_controller_impl.h",
     "fullscreen_controller_impl.mm",
@@ -63,8 +65,6 @@ source_set("internal") {
     "fullscreen_web_state_observer.mm",
     "fullscreen_web_view_proxy_observer.h",
     "fullscreen_web_view_proxy_observer.mm",
-    "fullscreen_web_view_scroll_view_replacement_util.h",
-    "fullscreen_web_view_scroll_view_replacement_util.mm",
   ]
 
   configs += [ "//build/config/compiler:enable_arc" ]
@@ -129,6 +129,7 @@ source_set("unit_tests") {
     "//ios/web/public",
     "//ios/web/public/test/fakes",
     "//testing/gtest",
+    "//third_party/ocmock",
   ]
 }
 

ios/chrome/browser/ui/fullscreen/fullscreen_web_view_scroll_view_replacement_util.h → ios/chrome/browser/ui/fullscreen/fullscreen_content_adjustment_util.h

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef IOS_CHROME_BROWSER_UI_FULLSCREEN_FULLSCREEN_WEB_VIEW_SCROLL_VIEW_REPLACEMENT_UTIL_H_
-#define IOS_CHROME_BROWSER_UI_FULLSCREEN_FULLSCREEN_WEB_VIEW_SCROLL_VIEW_REPLACEMENT_UTIL_H_
+#ifndef IOS_CHROME_BROWSER_UI_FULLSCREEN_FULLSCREEN_CONTENT_ADJUSTMENT_UTIL_H_
+#define IOS_CHROME_BROWSER_UI_FULLSCREEN_FULLSCREEN_CONTENT_ADJUSTMENT_UTIL_H_
 
 #import <Foundation/Foundation.h>
 
@@ -11,9 +11,7 @@
 class FullscreenModel;
 
 // Updates |proxy|'s content offset and top padding to ensure that the content
-// is fully visible under the toolbar when its scroll view is replaced.
-void UpdateFullscreenWebViewProxyForReplacedScrollView(
-    id<CRWWebViewProxy> proxy,
-    FullscreenModel* model);
+// is fully visible under the hdeader.
+void MoveContentBelowHeader(id<CRWWebViewProxy> proxy, FullscreenModel* model);
 
-#endif  // IOS_CHROME_BROWSER_UI_FULLSCREEN_FULLSCREEN_WEB_VIEW_SCROLL_VIEW_REPLACEMENT_UTIL_H_
+#endif  // IOS_CHROME_BROWSER_UI_FULLSCREEN_FULLSCREEN_CONTENT_ADJUSTMENT_UTIL_H_

ios/chrome/browser/ui/fullscreen/fullscreen_web_view_scroll_view_replacement_util.mm → ios/chrome/browser/ui/fullscreen/fullscreen_content_adjustment_util.mm

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#import "ios/chrome/browser/ui/fullscreen/fullscreen_web_view_scroll_view_replacement_util.h"
+#import "ios/chrome/browser/ui/fullscreen/fullscreen_content_adjustment_util.h"
 
 #include "base/logging.h"
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_model.h"
@@ -13,9 +13,7 @@
 #error "This file requires ARC support."
 #endif
 
-void UpdateFullscreenWebViewProxyForReplacedScrollView(
-    id<CRWWebViewProxy> proxy,
-    FullscreenModel* model) {
+void MoveContentBelowHeader(id<CRWWebViewProxy> proxy, FullscreenModel* model) {
   DCHECK(proxy);
   DCHECK(model);
   CGFloat padding = model->progress() * model->GetToolbarHeight();

ios/chrome/browser/ui/fullscreen/fullscreen_web_state_list_observer.h

@@ -5,6 +5,8 @@
 #ifndef IOS_CLEAN_CHROME_BROWSER_UI_FULLSCREEN_FULLSCREEN_WEB_STATE_LIST_OBSERVER_H_
 #define IOS_CLEAN_CHROME_BROWSER_UI_FULLSCREEN_FULLSCREEN_WEB_STATE_LIST_OBSERVER_H_
 
+#include <set>
+
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_web_state_observer.h"
 #import "ios/chrome/browser/web_state_list/web_state_list_observer.h"
 #include "ios/web/public/web_state/web_state_observer.h"
@@ -40,6 +42,16 @@ class FullscreenWebStateListObserver : public WebStateListObserver {
                            web::WebState* new_web_state,
                            int active_index,
                            int reason) override;
+  void WebStateDetachedAt(WebStateList* web_state_list,
+                          web::WebState* web_state,
+                          int index) override;
+  void WillCloseWebStateAt(WebStateList* web_state_list,
+                           web::WebState* web_state,
+                           int index,
+                           bool user_action) override;
+
+  // Whether |web_state| has been activated during the lifetime of this object.
+  bool HasWebStateBeenActivated(web::WebState* web_state);
 
   // The model passed on construction.
   FullscreenModel* model_;
@@ -47,6 +59,8 @@ class FullscreenWebStateListObserver : public WebStateListObserver {
   WebStateList* web_state_list_;
   // The observer for the active WebState.
   FullscreenWebStateObserver web_state_observer_;
+  // The WebStates that have been activated in |web_state_list_|.
+  std::set<web::WebState*> activated_web_states_;
 };
 
 #endif  // IOS_CLEAN_CHROME_BROWSER_UI_FULLSCREEN_FULLSCREEN_WEB_STATE_LIST_OBSERVER_H_

ios/chrome/browser/ui/fullscreen/fullscreen_web_state_list_observer.mm

@@ -5,8 +5,8 @@
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_web_state_list_observer.h"
 
 #include "base/logging.h"
+#import "ios/chrome/browser/ui/fullscreen/fullscreen_content_adjustment_util.h"
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_model.h"
-#import "ios/chrome/browser/ui/fullscreen/fullscreen_web_view_scroll_view_replacement_util.h"
 #import "ios/chrome/browser/web_state_list/web_state_list.h"
 #import "ios/web/public/web_state/web_state.h"
 
@@ -44,13 +44,15 @@ void FullscreenWebStateListObserver::WebStateReplacedAt(
     web::WebState* old_web_state,
     web::WebState* new_web_state,
     int index) {
+  if (HasWebStateBeenActivated(old_web_state))
+    activated_web_states_.erase(old_web_state);
   if (new_web_state == web_state_list->GetActiveWebState()) {
     // Reset the model if the active WebState is replaced.
     web_state_observer_.SetWebState(new_web_state);
     model_->ResetForNavigation();
     if (new_web_state) {
-      UpdateFullscreenWebViewProxyForReplacedScrollView(
-          new_web_state->GetWebViewProxy(), model_);
+      MoveContentBelowHeader(new_web_state->GetWebViewProxy(), model_);
+      activated_web_states_.insert(new_web_state);
     }
   }
 }
@@ -62,4 +64,32 @@ void FullscreenWebStateListObserver::WebStateActivatedAt(
     int active_index,
     int reason) {
   web_state_observer_.SetWebState(new_web_state);
+  // If this is the first time the WebState was activated, move its content
+  // below the header.
+  if (new_web_state && !HasWebStateBeenActivated(new_web_state)) {
+    MoveContentBelowHeader(new_web_state->GetWebViewProxy(), model_);
+    activated_web_states_.insert(new_web_state);
+  }
+}
+
+void FullscreenWebStateListObserver::WebStateDetachedAt(
+    WebStateList* web_state_list,
+    web::WebState* web_state,
+    int index) {
+  if (HasWebStateBeenActivated(web_state))
+    activated_web_states_.erase(web_state);
+}
+
+void FullscreenWebStateListObserver::WillCloseWebStateAt(
+    WebStateList* web_state_list,
+    web::WebState* web_state,
+    int index,
+    bool user_action) {
+  if (HasWebStateBeenActivated(web_state))
+    activated_web_states_.erase(web_state);
+}
+
+bool FullscreenWebStateListObserver::HasWebStateBeenActivated(
+    web::WebState* web_state) {
+  return activated_web_states_.find(web_state) != activated_web_states_.end();
 }

ios/chrome/browser/ui/fullscreen/fullscreen_web_state_list_observer_unittest.mm

@@ -18,12 +18,36 @@
 #import "ios/web/public/test/fakes/fake_navigation_context.h"
 #import "ios/web/public/test/fakes/test_navigation_manager.h"
 #import "ios/web/public/test/fakes/test_web_state.h"
+#import "ios/web/public/web_state/ui/crw_web_view_proxy.h"
+#import "ios/web/public/web_state/ui/crw_web_view_scroll_view_proxy.h"
 #include "testing/platform_test.h"
+#import "third_party/ocmock/OCMock/OCMock.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
+namespace {
+// A TestWebState subclass that returns mock objects for the view proxies.
+class TestWebStateWithProxy : public web::TestWebState {
+ public:
+  TestWebStateWithProxy() {
+    scroll_view_proxy_ = OCMClassMock([CRWWebViewScrollViewProxy class]);
+    id web_view_proxy_mock = OCMProtocolMock(@protocol(CRWWebViewProxy));
+    [[[web_view_proxy_mock stub] andReturn:scroll_view_proxy_] scrollViewProxy];
+    web_view_proxy_ = web_view_proxy_mock;
+  }
+  id<CRWWebViewProxy> GetWebViewProxy() const override {
+    return web_view_proxy_;
+  }
+
+ private:
+  // The mocked proxy objects.
+  __strong CRWWebViewScrollViewProxy* scroll_view_proxy_;
+  __strong id<CRWWebViewProxy> web_view_proxy_;
+};
+}  // namespace
+
 class FullscreenWebStateListObserverTest : public PlatformTest {
  public:
   FullscreenWebStateListObserverTest()
@@ -54,9 +78,9 @@ class FullscreenWebStateListObserverTest : public PlatformTest {
 TEST_F(FullscreenWebStateListObserverTest, ObserveActiveWebState) {
   // Insert a WebState into the list.  The observer should create a
   // FullscreenWebStateObserver for the newly activated WebState.
-  std::unique_ptr<web::TestWebState> inserted_web_state =
-      std::make_unique<web::TestWebState>();
-  web::TestWebState* web_state = inserted_web_state.get();
+  std::unique_ptr<TestWebStateWithProxy> inserted_web_state =
+      std::make_unique<TestWebStateWithProxy>();
+  TestWebStateWithProxy* web_state = inserted_web_state.get();
   web_state_list().InsertWebState(0, std::move(inserted_web_state),
                                   WebStateList::INSERT_ACTIVATE,
                                   WebStateOpener());

ios/chrome/browser/ui/fullscreen/fullscreen_web_view_proxy_observer.mm

@@ -5,9 +5,10 @@
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_web_view_proxy_observer.h"
 
 #include "base/logging.h"
+#import "ios/chrome/browser/ui/fullscreen/fullscreen_content_adjustment_util.h"
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_mediator.h"
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_model.h"
-#import "ios/chrome/browser/ui/fullscreen/fullscreen_web_view_scroll_view_replacement_util.h"
+#include "ios/chrome/browser/ui/ui_util.h"
 #import "ios/web/public/web_state/ui/crw_web_view_proxy.h"
 #import "ios/web/public/web_state/ui/crw_web_view_scroll_view_proxy.h"
 
@@ -51,7 +52,7 @@
 
 - (void)webViewScrollViewProxyDidSetScrollView:
     (CRWWebViewScrollViewProxy*)webViewScrollViewProxy {
-  UpdateFullscreenWebViewProxyForReplacedScrollView(self.proxy, self.model);
+  MoveContentBelowHeader(self.proxy, self.model);
 }
 
 - (BOOL)webViewScrollViewShouldScrollToTop: