[iOS] Move pdfs below headers when first loaded on iOS 11.

On iOS 12, resetting the WKScrollView.contentInset at the start of the
navigation pushes the content to {0, -contentInset.top}.  On iOS 11,
this does not occur.  This CL updates FullscreenWebStateObserver to
push the content below the toolbar the firs time a NavigationItem is
loaded with the shouldUseViewContentInset property set to YES.

This CL also updates MoveContentHelowHeader() to use the current top
toolbar inset rather than progress * extended toolbar height.  The
previous value was only working correctly because the function was
only called with a progress value of 1.0.

This CL re-enables FullscreenTestCase.testLongPDFInitialState, as
the behavior being tested is now fixed.

Bug: 904694, 903247
Change-Id: I134461e16054846a211a5476dd5a6694bd709002
Reviewed-on: https://chromium-review.googlesource.com/c/1371082
Commit-Queue: Kurt Horimoto <kkhorimoto@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615997}

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

@@ -17,7 +17,7 @@
 void MoveContentBelowHeader(id<CRWWebViewProxy> proxy, FullscreenModel* model) {
   DCHECK(proxy);
   DCHECK(model);
-  CGFloat topPadding = model->progress() * model->GetExpandedToolbarHeight();
+  CGFloat topPadding = model->current_toolbar_insets().top;
   proxy.scrollViewProxy.contentOffset = CGPointMake(0, -topPadding);
   if (!base::FeatureList::IsEnabled(web::features::kOutOfWebFullscreen)) {
     // With the fullscreen implementation living outside of web, this is no

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

@@ -85,10 +85,6 @@ void AssertURLIs(const GURL& expectedURL) {
 // Verifies that the content offset of the web view is set up at the correct
 // initial value when initially displaying a PDF.
 - (void)testLongPDFInitialState {
-  // TODO(crbug.com/904694): This test is failing on iOS11.
-  if (!base::ios::IsRunningOnIOS12OrLater())
-    EARL_GREY_TEST_DISABLED(@"Disabled on iOS 11.");
-
   web::test::SetUpFileBasedHttpServer();
   GURL URL = web::test::HttpServer::MakeUrl(
       "http://ios/testing/data/http_server_files/two_pages.pdf");
@@ -114,7 +110,12 @@ void AssertURLIs(const GURL& expectedURL) {
   }
   if (base::FeatureList::IsEnabled(
           web::features::kBrowserContainerFullscreen) &&
-      base::FeatureList::IsEnabled(web::features::kOutOfWebFullscreen)) {
+      base::FeatureList::IsEnabled(web::features::kOutOfWebFullscreen) &&
+      base::ios::IsRunningOnIOS12OrLater()) {
+    // In the fullscreen browser implementation, the safe area is included in
+    // the top inset as well as the toolbar heights.  Due to crbug.com/903635,
+    // however, this only occurs on iOS 12; pdf rendering does not correctly
+    // account for the safe area on iOS 11.
     yOffset -=
         chrome_test_util::GetCurrentWebState()->GetView().safeAreaInsets.top;
   }

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

@@ -82,6 +82,11 @@ TEST_F(FullscreenWebStateListObserverTest, ObserveActiveWebState) {
   std::unique_ptr<TestWebStateWithProxy> inserted_web_state =
       std::make_unique<TestWebStateWithProxy>();
   TestWebStateWithProxy* web_state = inserted_web_state.get();
+  std::unique_ptr<web::TestNavigationManager> passed_navigation_manager =
+      std::make_unique<web::TestNavigationManager>();
+  web::TestNavigationManager* navigation_manager =
+      passed_navigation_manager.get();
+  web_state->SetNavigationManager(std::move(passed_navigation_manager));
   web_state_list().InsertWebState(0, std::move(inserted_web_state),
                                   WebStateList::INSERT_ACTIVATE,
                                   WebStateOpener());
@@ -90,6 +95,9 @@ TEST_F(FullscreenWebStateListObserverTest, ObserveActiveWebState) {
   SimulateFullscreenUserScrollForProgress(&model(), 0.5);
   EXPECT_EQ(model().progress(), 0.5);
   // Simulate a navigation.  The model should be reset by the observers.
+  std::unique_ptr<web::NavigationItem> committed_item =
+      web::NavigationItem::Create();
+  navigation_manager->SetLastCommittedItem(committed_item.get());
   web::FakeNavigationContext context;
   web_state->OnNavigationFinished(&context);
   EXPECT_FALSE(model().has_base_offset());

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

@@ -4,7 +4,9 @@
 
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_web_state_observer.h"
 
+#include "base/ios/ios_util.h"
 #include "base/logging.h"
+#import "ios/chrome/browser/ui/fullscreen/fullscreen_content_adjustment_util.h"
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_features.h"
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_mediator.h"
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_model.h"
@@ -16,6 +18,7 @@
 #include "ios/web/public/ssl_status.h"
 #include "ios/web/public/url_util.h"
 #import "ios/web/public/web_state/navigation_context.h"
+#import "ios/web/public/web_state/page_display_state.h"
 #import "ios/web/public/web_state/ui/crw_web_view_proxy.h"
 #import "ios/web/public/web_state/web_state.h"
 
@@ -91,6 +94,7 @@ void FullscreenWebStateObserver::DidFinishNavigation(
   bool url_changed = web::GURLByRemovingRefFromGURL(navigation_url) !=
                      web::GURLByRemovingRefFromGURL(last_navigation_url_);
   last_navigation_url_ = navigation_url;
+
   // Due to limitations in WKWebView's rendering, different MIME types must be
   // inset using different techniques:
   // - PDFs need to be inset using the scroll view's |contentInset| property or
@@ -101,9 +105,23 @@ void FullscreenWebStateObserver::DidFinishNavigation(
   bool force_content_inset =
       fullscreen::features::GetActiveViewportExperiment() ==
       ViewportAdjustmentExperiment::CONTENT_INSET;
-  web_state->GetWebViewProxy().shouldUseViewContentInset =
-      force_content_inset ||
-      web_state->GetContentsMimeType() == "application/pdf";
+  bool is_pdf = web_state->GetContentsMimeType() == "application/pdf";
+  bool use_content_inset = force_content_inset || is_pdf;
+  id<CRWWebViewProxy> web_view_proxy = web_state->GetWebViewProxy();
+  web_view_proxy.shouldUseViewContentInset = use_content_inset;
+
+  // On iOS 12, resetting WKScrollView.contentInset at this point in the load
+  // will push the content down by the top inset.  On iOS 11, however, this does
+  // not occur.  Manually push the content below the toolbars the first time a
+  // page is loaded with the content inset setting enabled.  The scroll offset
+  // of subsequent loads of this navigation will be set by the PageDisplayState.
+  web::NavigationItem* committed_item =
+      web_state->GetNavigationManager()->GetLastCommittedItem();
+  if (use_content_inset && !base::ios::IsRunningOnIOS12OrLater() &&
+      !committed_item->GetPageDisplayState().IsValid()) {
+    MoveContentBelowHeader(web_view_proxy, model_);
+  }
+
   // Only reset the model for document-changing navigations or same-document
   // navigations that update the visible URL.
   if (!navigation_context->IsSameDocument() || url_changed)