Disable error page isolation in Android WebView.

Error page isolation requires process swaps and locking processes to
origin. It isn't clear Android WebView supports these quite yet, so
disable this feature for now.

Bug: 800544, 838161
Change-Id: Idb5c4a22aee3c6d40560a7676a7659d9101ee2e8
Reviewed-on: https://chromium-review.googlesource.com/c/1310566Reviewed-by: Bo <boliu@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Commit-Queue: Nasko Oskov <nasko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604371}

android_webview/browser/aw_content_browser_client.cc

@@ -758,6 +758,10 @@ void AwContentBrowserClient::RegisterOutOfProcessServices(
       base::BindRepeating(&base::ASCIIToUTF16, "Heap Profiling Service");
 }
 
+bool AwContentBrowserClient::ShouldIsolateErrorPage(bool in_main_frame) {
+  return false;
+}
+
 bool AwContentBrowserClient::ShouldEnableStrictSiteIsolation() {
   // TODO(lukasza): When/if we eventually add OOPIF support for AW we should
   // consider running AW tests with and without site-per-process (and this might

android_webview/browser/aw_content_browser_client.h

@@ -202,6 +202,7 @@ class AwContentBrowserClient : public content::ContentBrowserClient {
       ui::PageTransition page_transition,
       bool has_user_gesture) override;
   void RegisterOutOfProcessServices(OutOfProcessServiceMap* services) override;
+  bool ShouldIsolateErrorPage(bool in_main_frame) override;
   bool ShouldEnableStrictSiteIsolation() override;
   bool WillCreateURLLoaderFactory(
       content::BrowserContext* browser_context,