Add a NavigationThrottle to the public content/ interface

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index cadc2bc89f51e56ee1bbbd3c273d6fa0d08f7ae4..63f5e46dd49b63ebd5843b4a6138caca3c492523 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -24,6 +24,7 @@
 #include "base/thread_task_runner_handle.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/after_startup_task_utils.h"
+#include "chrome/browser/apps/app_url_redirector.h"
 #include "chrome/browser/browser_about_handler.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/browser_shutdown.h"
@@ -104,6 +105,7 @@
 #include "components/dom_distiller/core/url_constants.h"
 #include "components/google/core/browser/google_util.h"
 #include "components/metrics/client_info.h"
+#include "components/navigation_interception/intercept_navigation_delegate.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/rappor/rappor_utils.h"
 #include "components/signin/core/common/profile_management_switches.h"
@@ -119,6 +121,7 @@
 #include "content/public/browser/child_process_data.h"
 #include "content/public/browser/child_process_security_policy.h"
 #include "content/public/browser/client_certificate_delegate.h"
+#include "content/public/browser/navigation_throttle.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
@@ -2546,6 +2549,31 @@ void ChromeContentBrowserClient::RecordURLMetric(const std::string& metric,
   }
 }
 
+void ChromeContentBrowserClient::AddNavigationThrottles(
+    content::NavigationHandle* handle,
+    WebContents* web_contents) {
+#if defined(OS_ANDROID)
+  // TODO(davidben): This is insufficient to integrate with prerender properly.
+  // https://crbug.com/370595
+  prerender::PrerenderContents* prerender_contents =
+      prerender::PrerenderContents::FromWebContents(web_contents);
+  if (!prerender_contents && handle->IsInMainFrame()) {
+    handle->RegisterThrottle(
+        navigation_interception::InterceptNavigationDelegate::CreateThrottleFor(
+            handle, web_contents));
+  }
+#else
+  if (handle->IsInMainFrame()) {
+    // Redirect some navigations to apps that have registered matching URL
+    // handlers ('url_handlers' in the manifest).
+    scoped_ptr<content::NavigationThrottle> url_to_app_throttle =
+        AppUrlRedirector::MaybeCreateThrottleFor(handle, web_contents);
+    if (url_to_app_throttle)
+      handle->RegisterThrottle(url_to_app_throttle.Pass());
+  }

[Avi (use Gerrit), 2015/09/01 16:38:47]

Do we really want to do this for every WebContents everywhere? Do we at least
want to make sure that it's a browser tab?

[davidben, 2015/09/01 21:55:17]

+1. If we can manage it, I think WebContentsDelegate seems a better place to
latch this onto. As a bonus, that prerender block can just go away. Though I
dunno if in practice we'll want a global one too.

[clamy, 2015/09/03 15:30:51]

I initially put that in WebContentsDelegate, but it did not work. The reason is
that some apps need the AppURLRedirector to be installed, even if their
WebContentsDelegate is an ExtensionHost. This particular class does not have
access to /chrome (as per /extension DEPS), which is where the AppURLRedirector
is located. I also become worried that we would have to duplicate the logic in
many different WebContentsDelegate.

Note that this is not a regression, as currently the ResourceThrottles are
installed on all requests.

+#endif
+}
+
 content::DevToolsManagerDelegate*
 ChromeContentBrowserClient::GetDevToolsManagerDelegate() {
   return new ChromeDevToolsManagerDelegate();