WebView: Add channel info for UMA

android_webview/browser/aw_metrics_service_client.h

Index: android_webview/browser/aw_metrics_service_client.h
diff --git a/android_webview/browser/aw_metrics_service_client.h b/android_webview/browser/aw_metrics_service_client.h
index b68d215271fa148d531f63d228d53ff7eaf57efa..733bd6bce44ff88b3d686a6e4c38013d5b63901c 100644
--- a/android_webview/browser/aw_metrics_service_client.h
+++ b/android_webview/browser/aw_metrics_service_client.h
@@ -14,6 +14,7 @@
 #include "components/metrics/enabled_state_provider.h"
 #include "components/metrics/metrics_log_uploader.h"
 #include "components/metrics/metrics_service_client.h"
+#include "components/version_info/channel.h"
 
 class PrefService;
 
@@ -85,6 +86,7 @@ class AwMetricsServiceClient : public metrics::MetricsServiceClient,
   net::URLRequestContextGetter* request_context_;
   std::unique_ptr<metrics::MetricsStateManager> metrics_state_manager_;
   std::unique_ptr<metrics::MetricsService> metrics_service_;
+  version_info::Channel channel_;
 
   DISALLOW_COPY_AND_ASSIGN(AwMetricsServiceClient);
 };