Add UMA Histogram Manager to Cronet.

components/cronet.gypi

Index: components/cronet.gypi
diff --git a/components/cronet.gypi b/components/cronet.gypi
index e2a6f08af335c4663f5fac54aed8de4e59443a4e..8bdb4094d114a097207d98f603120055081c2fe2 100644
--- a/components/cronet.gypi
+++ b/components/cronet.gypi
@@ -15,6 +15,7 @@
             'cronet/android/java/src/org/chromium/net/CronetUrlRequestContext.java',
             'cronet/android/java/src/org/chromium/net/ChromiumUrlRequest.java',
             'cronet/android/java/src/org/chromium/net/ChromiumUrlRequestContext.java',
+            'cronet/android/java/src/org/chromium/net/HistogramManager.java',
           ],
           'variables': {
             'jni_gen_package': 'cronet',
@@ -107,6 +108,7 @@
             'cronet_url_request_context_config_list',
             'cronet_url_request_java',
             'cronet_version',
+            'metrics',
             '../net/net.gyp:net',
           ],
           'sources': [
@@ -129,6 +131,8 @@
             'cronet/android/cronet_url_request_context.h',
             'cronet/android/cronet_url_request_context_adapter.cc',
             'cronet/android/cronet_url_request_context_adapter.h',
+            'cronet/android/histogram_manager.cc',
+            'cronet/android/histogram_manager.h',
             'cronet/android/url_request_adapter.cc',
             'cronet/android/url_request_adapter.h',
             'cronet/android/url_request_context_adapter.cc',
@@ -229,6 +233,7 @@
               '**/CronetUrlRequest.java',
               '**/CronetUrlRequestContext.java',
               '**/CronetUrlRequestFactory.java',
+              '**/HistogramManager.java',
               '**/RequestPriority.java',
               '**/urlconnection/CronetInputStream.java',
               '**/urlconnection/CronetHttpURLConnection.java',