[iOS] Change the computation of the PDF insets

This CL changes how the computation of the content insets of the scroll
view displaying the PDF is done on iOS 11.

Bug: 903635
Change-Id: I5dc8d69b4fbf0a6e68db1481f1991c9bdbc0b43b
Reviewed-on: https://chromium-review.googlesource.com/c/1341988
Commit-Queue: Kurt Horimoto <kkhorimoto@chromium.org>
Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609510}

ios/chrome/browser/ui/browser_view_controller.mm

@@ -3671,9 +3671,15 @@ applicationCommandEndpoint:(id<ApplicationCommands>)applicationCommandEndpoint
 
 - (CGFloat)overscrollActionsControllerHeaderInset:
     (OverscrollActionsController*)controller {
-  if (controller == [[[self tabModel] currentTab] overscrollActionsController])
-    return self.headerHeight;
-  else
+  if (controller ==
+      [[[self tabModel] currentTab] overscrollActionsController]) {
+    if (!base::ios::IsRunningOnIOS12OrLater() &&
+        self.currentWebState->GetContentsMimeType() == "application/pdf") {
+      return self.headerHeight - self.view.safeAreaInsets.top;
+    } else {
+      return self.headerHeight;
+    }
+  } else
     return 0;
 }
 

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

@@ -4,6 +4,7 @@
 
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_web_view_resizer.h"
 
+#include "base/ios/ios_util.h"
 #include "ios/chrome/browser/chrome_url_constants.h"
 #import "ios/chrome/browser/ui/fullscreen/fullscreen_model.h"
 #import "ios/chrome/browser/ui/util/uikit_ui_util.h"
@@ -112,6 +113,9 @@
   CRWWebViewScrollViewProxy* scrollViewProxy = webViewProxy.scrollViewProxy;
 
   if (self.webState->GetContentsMimeType() == "application/pdf") {
+    if (!base::ios::IsRunningOnIOS12OrLater()) {
+      insets.top -= webView.safeAreaInsets.top;
+    }
     scrollViewProxy.contentInset = insets;
     if (!CGRectEqualToRect(webView.frame, webView.superview.bounds)) {
       webView.frame = webView.superview.bounds;