[Cronet] Allow UrlRequest bypass cache

components/cronet/android/cronet_url_request_adapter.cc

Index: components/cronet/android/cronet_url_request_adapter.cc
diff --git a/components/cronet/android/cronet_url_request_adapter.cc b/components/cronet/android/cronet_url_request_adapter.cc
index 265895af4512a5ab4f932c5d8e4d9a1942f6799e..c032afc3b70b29782e60cee2bb94bfaf484c2a4c 100644
--- a/components/cronet/android/cronet_url_request_adapter.cc
+++ b/components/cronet/android/cronet_url_request_adapter.cc
@@ -28,7 +28,8 @@ CronetURLRequestAdapter::CronetURLRequestAdapter(
       delegate_(delegate.Pass()),
       initial_url_(url),
       initial_priority_(priority),
-      initial_method_("GET") {
+      initial_method_("GET"),
+      bypass_cache_(false) {
 }
 
 CronetURLRequestAdapter::~CronetURLRequestAdapter() {
@@ -41,6 +42,11 @@ void CronetURLRequestAdapter::AddRequestHeader(const std::string& name,
   initial_request_headers_.SetHeader(name, value);
 }
 
+void CronetURLRequestAdapter::BypassCache() {
+  DCHECK(!IsOnNetworkThread());
+  bypass_cache_ = true;
+}
+
 bool CronetURLRequestAdapter::PostTaskToNetworkThread(
     const tracked_objects::Location& from_here,
     const base::Closure& task) {
@@ -59,7 +65,10 @@ void CronetURLRequestAdapter::Start() {
           << " priority: " << RequestPriorityToString(initial_priority_);
   url_request_ = context_->GetURLRequestContext()->CreateRequest(
       initial_url_, net::DEFAULT_PRIORITY, this, NULL);
-  url_request_->SetLoadFlags(context_->default_load_flags());
+  int load_flags = context_->default_load_flags();

[mef, 2015/01/30 16:06:08]

Would it make sense to make |load_flags_| a member variable, which is
initialized by context_->default_load_flags() in constructor?

BypassCache() would set net::LOAD_DISABLE_CACHE.

Start() would use load_flags_ instead of default_load_flags().

[xunjieli, 2015/01/30 22:39:46]

Done.

+  if (bypass_cache_)
+    load_flags |= net::LOAD_DISABLE_CACHE;
+  url_request_->SetLoadFlags(load_flags);
   url_request_->set_method(initial_method_);
   url_request_->SetExtraRequestHeaders(initial_request_headers_);
   url_request_->SetPriority(initial_priority_);