Refactor to make BlimpLocationProvider accessible to content layer.

content/browser/geolocation/location_arbitrator_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/geolocation/location_arbitrator_impl.h"
 
 #include <map>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 34 matching lines @@
   return GURL(kDefaultNetworkProviderUrl);
 }
 
 void LocationArbitratorImpl::OnPermissionGranted() {
   is_permission_granted_ = true;
   for (const auto& provider : providers_)
     provider->OnPermissionGranted();
 }
 
 void LocationArbitratorImpl::StartProviders(bool enable_high_accuracy) {
-  // GetAccessTokenStore() will return NULL for embedders not implementing
-  // the AccessTokenStore class, so we report an error to avoid JavaScript
-  // requests of location to wait eternally for a reply.
-  AccessTokenStore* access_token_store = GetAccessTokenStore();
-  if (!access_token_store) {
+  // Stash options as OnAccessTokenStoresLoaded has not yet been called.
+  is_running_ = true;
+  enable_high_accuracy_ = enable_high_accuracy;
+
+  if (providers_.empty()) {
+    RegisterSystemProvider();
+
+    AccessTokenStore* access_token_store = GetAccessTokenStore();
+    if (access_token_store &&
+        GetContentClient()->browser()->UseNetworkLocationProviders()) {
+      DCHECK(DefaultNetworkProviderURL().is_valid());
+      token_store_callback_.Reset(
+          base::Bind(&LocationArbitratorImpl::OnAccessTokenStoresLoaded,
+                     base::Unretained(this)));
+      access_token_store->LoadAccessTokens(token_store_callback_.callback());
+      return;
+    }
+  }
+  DoStartProviders();
+}
+
+void LocationArbitratorImpl::DoStartProviders() {
+  if (providers_.empty()) {
+    // GetAccessTokenStore() will return NULL for embedders not implementing
+    // the AccessTokenStore class, so we report an error to avoid JavaScript
+    // requests of location to wait eternally for a reply.

[Wez, 2016/06/10 23:40:34]

nit: Strange wording; I think you mean ".. to avoid JS callers waiting
indefinitely for a reply."?

This seems less to avoid JS waiting indefinitely, and more to be a simple case
of that being the way the API is suppose to work - that it returns an error if
it cannot succeed?

[CJ, 2016/06/13 23:45:20]

I didn't write the comment, just have been trying to keep it with the code it
belongs with, so my insight into why it is written in such a way is limited.
Updating according to your feedback, making it more about the general error
handling. 

     Geoposition position;
     position.error_code = Geoposition::ERROR_CODE_PERMISSION_DENIED;
     arbitrator_update_callback_.Run(position);
     return;
   }
-
-  // Stash options as OnAccessTokenStoresLoaded has not yet been called.
-  is_running_ = true;
-  enable_high_accuracy_ = enable_high_accuracy;
-  if (providers_.empty()) {
-    DCHECK(DefaultNetworkProviderURL().is_valid());
-    access_token_store->LoadAccessTokens(
-        base::Bind(&LocationArbitratorImpl::OnAccessTokenStoresLoaded,
-                   base::Unretained(this)));
-  } else {
-    DoStartProviders();
-  }
-}
-
-void LocationArbitratorImpl::DoStartProviders() {
   for (const auto& provider : providers_)
     provider->StartProvider(enable_high_accuracy_);
 }
 
 void LocationArbitratorImpl::StopProviders() {
   // Reset the reference location state (provider+position)
   // so that future starts use fresh locations from
   // the newly constructed providers.
   position_provider_ = NULL;
   position_ = Geoposition();
 
   providers_.clear();
   is_running_ = false;
 }
 
 void LocationArbitratorImpl::OnAccessTokenStoresLoaded(
     AccessTokenStore::AccessTokenMap access_token_map,
     net::URLRequestContextGetter* context_getter) {
-  if (!is_running_ || !providers_.empty()) {
-    // A second StartProviders() call may have arrived before the first
-    // completed.
-    return;
-  }
   // If there are no access tokens, boot strap it with the default server URL.
   if (access_token_map.empty())
     access_token_map[DefaultNetworkProviderURL()];
   for (const auto& entry : access_token_map) {
     RegisterProvider(NewNetworkLocationProvider(
         GetAccessTokenStore(), context_getter, entry.first, entry.second));
   }
-
-  LocationProvider* provider =
-      GetContentClient()->browser()->OverrideSystemLocationProvider();
-  if (!provider)
-    provider = NewSystemLocationProvider();
-  RegisterProvider(provider);
   DoStartProviders();
 }
 
 void LocationArbitratorImpl::RegisterProvider(
     LocationProvider* provider) {
   if (!provider)
     return;
   provider->SetUpdateCallback(provider_update_callback_);
   if (is_permission_granted_)
     provider->OnPermissionGranted();
   providers_.push_back(provider);
 }
 
+void LocationArbitratorImpl::RegisterSystemProvider() {
+  LocationProvider* provider =
+      GetContentClient()->browser()->OverrideSystemLocationProvider();
+  if (!provider)
+    provider = NewSystemLocationProvider();
+  RegisterProvider(provider);
+}
+
 void LocationArbitratorImpl::OnLocationUpdate(const LocationProvider* provider,
                                               const Geoposition& new_position) {
   DCHECK(new_position.Validate() ||
          new_position.error_code != Geoposition::ERROR_CODE_NONE);
   if (!IsNewPositionBetter(position_, new_position,
                            provider == position_provider_))
     return;
   position_provider_ = provider;
   position_ = new_position;
   arbitrator_update_callback_.Run(position_);
@@ skipping 59 matching lines @@
     }
   }
   return false;
 }
 
 bool LocationArbitratorImpl::HasPermissionBeenGranted() const {
   return is_permission_granted_;
 }
 
 }  // namespace content