Disable Opt-in origin isolation on Android Webview.

This CL makes ShouldDisableSiteIsolation() return true on Android
Webview.  This will turns off features like opt-in origin isolation that
rely on site isolation and OOPIFs on that platform, much like we also
turn them off on Chrome for Android when below a memory threshold.

Change-Id: I827ff79bd9955b90a58986ec0e1552743c194331
Bug: 1147327
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2528307
Commit-Queue: Alex Moshchuk <alexmos@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Reviewed-by: James MacLean <wjmaclean@chromium.org>
Reviewed-by: Łukasz Anforowicz <lukasza@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826051}

android_webview/browser/aw_content_browser_client.cc

@@ -881,14 +881,22 @@ 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
   // require returning true below).  Adding OOPIF support for AW is tracked by
-  // https://crbug.com/869494.
+  // https://crbug.com/806404.
   return false;
 }
 
+bool AwContentBrowserClient::ShouldDisableSiteIsolation() {
+  // Since AW does not yet support OOPIFs, we must return true here to disable
+  // features that may trigger OOPIFs, such as origin isolation.
+  //
+  // Adding OOPIF support for AW is tracked by https://crbug.com/806404.
+  return true;
+}
+
 bool AwContentBrowserClient::ShouldLockProcessToSite(
     content::BrowserContext* browser_context,
     const GURL& effective_url) {
-  // TODO(lukasza): https://crbug.cmo/869494: Once Android WebView supports
+  // TODO(lukasza): https://crbug.com/806404: Once Android WebView supports
   // OOPIFs, we should remove this ShouldLockProcess overload.  Till then,
   // returning false helps avoid accidentally applying citadel-style Site
   // Isolation enforcement to Android WebView (and causing incorrect renderer

android_webview/browser/aw_content_browser_client.h

@@ -189,6 +189,7 @@ class AwContentBrowserClient : public content::ContentBrowserClient {
       NonNetworkURLLoaderFactoryMap* factories) override;
   bool ShouldIsolateErrorPage(bool in_main_frame) override;
   bool ShouldEnableStrictSiteIsolation() override;
+  bool ShouldDisableSiteIsolation() override;
   bool ShouldLockProcessToSite(content::BrowserContext* browser_context,
                                const GURL& effective_url) override;
   bool WillCreateURLLoaderFactory(

content/public/browser/content_browser_client.h

@@ -552,14 +552,17 @@ class CONTENT_EXPORT ContentBrowserClient {
   virtual std::vector<url::Origin> GetOriginsRequiringDedicatedProcess();
 
   // Allows the embedder to programmatically control whether the
-  // --site-per-process mode of Site Isolation should be used.
+  // --site-per-process mode of Site Isolation should be used.  Note that
+  // returning true here will only take effect if ShouldDisableSiteIsolation()
+  // below returns false.
   //
   // Note that for correctness, the same value should be consistently returned.
   // See also https://crbug.com/825369
   virtual bool ShouldEnableStrictSiteIsolation();
 
   // Allows the embedder to programmatically control whether Site Isolation
-  // should be disabled.
+  // should be disabled.  Note that this takes precedence over
+  // ShouldEnableStrictSiteIsolation() if both return true.
   //
   // Note that for correctness, the same value should be consistently returned.
   virtual bool ShouldDisableSiteIsolation();