AW: make contextgetter's http cache in memory

Default code path is unchanged, this only changes behavior when the
network service is enabled.

This changes AwURLRequestContextGetter's HTTP cache to be in-memory when
the network service is enabled, to avoid creating a second HTTP cache
(in addition to the NetworkContext's cache).

R=jam@chromium.org

Bug: 887538
Test: N/A
Change-Id: I13073e68a46d6eedaca6d77cf2f96b3ea84fdecb
Cq-Include-Trybots: master.tryserver.chromium.android:android_mojo
Reviewed-on: https://chromium-review.googlesource.com/c/1319334Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605762}

android_webview/browser/net/aw_url_request_context_getter.cc

@@ -21,6 +21,7 @@
 #include "base/base_paths_android.h"
 #include "base/bind.h"
 #include "base/command_line.h"
+#include "base/feature_list.h"
 #include "base/files/file_path.h"
 #include "base/path_service.h"
 #include "base/strings/string_number_conversions.h"
@@ -65,6 +66,7 @@
 #include "net/url_request/url_request_context_builder.h"
 #include "net/url_request/url_request_intercepting_job_factory.h"
 #include "net/url_request/url_request_interceptor.h"
+#include "services/network/public/cpp/features.h"
 #include "services/network/public/cpp/network_switches.h"
 
 using base::FilePath;
@@ -306,8 +308,13 @@ void AwURLRequestContextGetter::InitializeURLRequestContext() {
                                       std::move(channel_id_service));
 
   net::URLRequestContextBuilder::HttpCacheParams cache_params;
+  // Note: we create this as IN_MEMORY when the network service is enabled
+  // only as a temporary measure, to avoid accessing the same HTTP cache from
+  // two spots in the code.
   cache_params.type =
-      net::URLRequestContextBuilder::HttpCacheParams::DISK_SIMPLE;
+      base::FeatureList::IsEnabled(network::features::kNetworkService)
+          ? net::URLRequestContextBuilder::HttpCacheParams::IN_MEMORY
+          : net::URLRequestContextBuilder::HttpCacheParams::DISK_SIMPLE;
   cache_params.max_size = 20 * 1024 * 1024;  // 20M
   cache_params.path = cache_path_;
   builder.EnableHttpCache(cache_params);