[Android] Support the feature of proxy in Crosswalk

Crosswalk for android will update proxy when a PROXY_CHANGE intent is received,
but it’s need system permission to send the broadcast, there is also a workaround with
reflecting the incompatible api, but it’s too complex to maintain those codes, so
implement the new API in XWalkView to set proxy for images/text resources.

BUG=XWALK-6769

net/proxy/proxy_config_service_android.cc

@@ -411,4 +411,12 @@ void ProxyConfigServiceAndroid::ProxySettingsChanged() {
   delegate_->ProxySettingsChanged();
 }
 
+void ProxyConfigServiceAndroid::ProxySettingsChangedTo(
+    const std::string& host,
+    int port,
+    const std::string& pac_url,
+    const std::vector<std::string>& exclusion_list) {
+  delegate_->ProxySettingsChangedTo(host, port, pac_url, exclusion_list);
+}
+
 } // namespace net

net/proxy/proxy_config_service_android.h

@@ -6,6 +6,7 @@
 #define NET_PROXY_PROXY_CONFIG_SERVICE_ANDROID_H_
 
 #include <string>
+#include <vector>
 
 #include "base/android/jni_android.h"
 #include "base/callback_forward.h"
@@ -78,6 +79,12 @@ class NET_EXPORT ProxyConfigServiceAndroid : public ProxyConfigService {
   void RemoveObserver(Observer* observer) override;
   ConfigAvailability GetLatestProxyConfig(ProxyConfig* config) override;
 
+  void ProxySettingsChanged();
+  void ProxySettingsChangedTo(const std::string& host,
+                              int port,
+                              const std::string& pac_url,
+                              const std::vector<std::string>& exclusion_list);
+
  private:
   friend class ProxyConfigServiceAndroidTestBase;
   class Delegate;
@@ -88,9 +95,6 @@ class NET_EXPORT ProxyConfigServiceAndroid : public ProxyConfigService {
       const scoped_refptr<base::SequencedTaskRunner>& jni_task_runner,
       GetPropertyCallback get_property_callback);
 
-  // For tests.
-  void ProxySettingsChanged();
-
   scoped_refptr<Delegate> delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyConfigServiceAndroid);

net/proxy/proxy_service.cc

@@ -1475,6 +1475,11 @@ ProxyService::State ProxyService::ResetProxyConfig(bool reset_fetched_config) {
   return previous_state;
 }
 
+ProxyConfigService* ProxyService::GetProxyConfigService() const {
+  DCHECK(CalledOnValidThread());
+  return config_service_.get();
+}
+
 void ProxyService::ResetConfigService(
     scoped_ptr<ProxyConfigService> new_proxy_config_service) {
   DCHECK(CalledOnValidThread());

net/proxy/proxy_service.h

@@ -215,6 +215,7 @@ class NET_EXPORT ProxyService : public NetworkChangeNotifier::IPAddressObserver,
   // ResolveProxy calls.
   void ResetConfigService(
       scoped_ptr<ProxyConfigService> new_proxy_config_service);
+  ProxyConfigService* GetProxyConfigService() const;
 
   // Returns the last configuration fetched from ProxyConfigService.
   const ProxyConfig& fetched_config() {