Reload offline version on load failure

ios/web/web_state/ui/crw_web_controller.mm

Index: ios/web/web_state/ui/crw_web_controller.mm
diff --git a/ios/web/web_state/ui/crw_web_controller.mm b/ios/web/web_state/ui/crw_web_controller.mm
index 31356fbb2a44a2876d05b1a63083384a7cc2d317..4db5b1c4143f46969394f1d6b91a4797d0127aed 100644
--- a/ios/web/web_state/ui/crw_web_controller.mm
+++ b/ios/web/web_state/ui/crw_web_controller.mm
@@ -1201,6 +1201,8 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
       // Don't create the web view; let it be lazy created as needed.
     } else {
       [self clearTransientContentView];
+      if ([self.nativeController respondsToSelector:@selector(willBeDismissed)])
+        [self.nativeController willBeDismissed];
       [self removeWebViewAllowingCachedReconstruction:YES];
       _touchTrackingRecognizer.get().touchTrackingDelegate = nil;
       _touchTrackingRecognizer.reset();
@@ -1278,6 +1280,8 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
 
   self.nativeProvider = nil;
   self.swipeRecognizerProvider = nil;
+  if ([self.nativeController respondsToSelector:@selector(willBeDismissed)])
+    [self.nativeController willBeDismissed];
   if ([self.nativeController respondsToSelector:@selector(close)])
     [self.nativeController close];
 
@@ -2018,6 +2022,9 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
   // addPendingEntry is called.
 
   [_delegate webWillInitiateLoadWithParams:params];
+  if ([self.nativeController respondsToSelector:@selector(willBeDismissed)]) {
+    [self.nativeController willBeDismissed];
+  }
 
   GURL navUrl = params.url;
   ui::PageTransition transition = params.transition_type;
@@ -2076,6 +2083,9 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
   // Reset current WebUI if one exists.
   [self clearWebUI];
 
+  if ([self.nativeController respondsToSelector:@selector(willBeDismissed)])
+    [self.nativeController willBeDismissed];

[Eugene But (OOO till 7-30), 2016/12/19 18:47:05]

It looks like |willBeDismissed| should be called only when
|clearTransientContentView| is called. To make this more maintainable, could you
please rename |clearTransientContentView| and move |willBeDismissed| call to
that renamed method.

[Olivier, 2016/12/20 12:29:47]

Done.

+
   // Abort any outstanding page load. This ensures the delegate gets informed
   // about the outgoing page, and further messages from the page are suppressed.
   if (_loadPhase != web::PAGE_LOADED)
@@ -2279,6 +2289,9 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
 
   if (!_webStateImpl->IsShowingWebInterstitial())
     [self recordStateInHistory];
+  if ([self.nativeController respondsToSelector:@selector(willBeDismissed)])

[Eugene But (OOO till 7-30), 2016/12/19 18:47:05]

|goToItemAtIndex:| calls |loadCurrentURL| or |loadWithParams|, and those 2
methods call willBeDismissed. So you probably don't need it here. 

[Olivier, 2016/12/20 12:29:47]

Done.

+    [self.nativeController willBeDismissed];
+
   CRWSessionEntry* fromEntry = self.sessionController.currentEntry;
 
   NSUserDefaults* userDefaults = [NSUserDefaults standardUserDefaults];
@@ -4863,6 +4876,8 @@ const NSTimeInterval kSnapshotOverlayTransition = 0.5;
 - (void)loadHTML:(NSString*)HTML forURL:(const GURL&)URL {
   // Remove the transient content view.
   [self clearTransientContentView];
+  if ([self.nativeController respondsToSelector:@selector(willBeDismissed)])
+    [self.nativeController willBeDismissed];
 
   _loadPhase = web::LOAD_REQUESTED;