Add Physical Web omnibox support for Android

This adds some degree of feature parity with iOS, which also has a
Physical Web omnibox completion and zero-suggest feature.

BUG=663842

Review-Url: https://codereview.chromium.org/2604243002
Cr-Commit-Position: refs/heads/master@{#442024}

chrome/browser/android/omnibox/autocomplete_controller_android.cc

@@ -185,7 +185,9 @@ void AutocompleteControllerAndroid::OnOmniboxFocused(
 
   // If omnibox text is empty, set it to the current URL for the purposes of
   // populating the verbatim match.
-  if (omnibox_text.empty())
+  if (omnibox_text.empty() &&
+      !current_url.SchemeIs(content::kChromeUIScheme) &&
+      !current_url.SchemeIs(chrome::kChromeUINativeScheme))
     omnibox_text = url;
 
   input_ = AutocompleteInput(

chrome/browser/autocomplete/chrome_autocomplete_provider_client.cc

@@ -17,6 +17,7 @@
 #include "chrome/browser/bitmap_fetcher/bitmap_fetcher_service.h"
 #include "chrome/browser/bitmap_fetcher/bitmap_fetcher_service_factory.h"
 #include "chrome/browser/bookmarks/bookmark_model_factory.h"
+#include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/history/history_service_factory.h"
 #include "chrome/browser/history/top_sites_factory.h"
@@ -153,7 +154,7 @@ ChromeAutocompleteProviderClient::GetKeywordExtensionsDelegate(
 
 physical_web::PhysicalWebDataSource*
 ChromeAutocompleteProviderClient::GetPhysicalWebDataSource() {
-  return nullptr;
+  return g_browser_process->GetPhysicalWebDataSource();
 }
 
 std::string ChromeAutocompleteProviderClient::GetAcceptLanguages() const {

components/omnibox/browser/autocomplete_classifier.cc

@@ -17,8 +17,11 @@
 
 // static
 const int AutocompleteClassifier::kDefaultOmniboxProviders =
-#if !defined(OS_ANDROID) && !defined(OS_IOS)
-    // Custom search engines cannot be used on mobile..
+#if defined(OS_ANDROID) || defined(OS_IOS)
+    // The Physical Web currently is only implemented on mobile devices.
+    AutocompleteProvider::TYPE_PHYSICAL_WEB |
+#else
+    // Custom search engines cannot be used on mobile.
     AutocompleteProvider::TYPE_KEYWORD |
 #endif
 #if !defined(OS_IOS)
@@ -29,8 +32,6 @@ const int AutocompleteClassifier::kDefaultOmniboxProviders =
 #else
     // "URL from clipboard" can only be used on iOS.
     AutocompleteProvider::TYPE_CLIPBOARD_URL |
-    // Physical Web omnibox results are only implemented on iOS.
-    AutocompleteProvider::TYPE_PHYSICAL_WEB |
 #endif
     AutocompleteProvider::TYPE_BOOKMARK |
     AutocompleteProvider::TYPE_HISTORY_QUICK |