Add missing (and remove superfluous) 'explicit' from constructors.

content/browser/plugin_service_impl_browsertest.cc

Index: content/browser/plugin_service_impl_browsertest.cc
diff --git a/content/browser/plugin_service_impl_browsertest.cc b/content/browser/plugin_service_impl_browsertest.cc
index 18780355dd64c61f2217f58fb7bb3f74197dca1a..9718a3fb19c639689844ad83a01d3063cf1fc4f3 100644
--- a/content/browser/plugin_service_impl_browsertest.cc
+++ b/content/browser/plugin_service_impl_browsertest.cc
@@ -36,7 +36,7 @@ void OpenChannel(PluginProcessHost::Client* client) {
 class MockPluginProcessHostClient : public PluginProcessHost::Client,
                                     public IPC::Listener {
  public:
-  MockPluginProcessHostClient(ResourceContext* context)
+  explicit MockPluginProcessHostClient(ResourceContext* context)
       : context_(context),
         channel_(NULL),
         set_plugin_info_called_(false) {
@@ -151,7 +151,7 @@ IN_PROC_BROWSER_TEST_F(PluginServiceTest, OpenChannelToPlugin) {
 // called since the request should get canceled before then.
 class MockCanceledPluginServiceClient : public PluginProcessHost::Client {
  public:
-  MockCanceledPluginServiceClient(ResourceContext* context)
+  explicit MockCanceledPluginServiceClient(ResourceContext* context)
       : context_(context),
         get_resource_context_called_(false) {
   }
@@ -214,7 +214,7 @@ IN_PROC_BROWSER_TEST_F(PluginServiceTest, CancelOpenChannelToPluginService) {
 class MockCanceledBeforeSentPluginProcessHostClient
     : public MockCanceledPluginServiceClient {
  public:
-  MockCanceledBeforeSentPluginProcessHostClient(
+  explicit MockCanceledBeforeSentPluginProcessHostClient(
       ResourceContext* context)
       : MockCanceledPluginServiceClient(context),
         set_plugin_info_called_(false),
@@ -289,7 +289,7 @@ IN_PROC_BROWSER_TEST_F(
 class MockCanceledAfterSentPluginProcessHostClient
     : public MockCanceledBeforeSentPluginProcessHostClient {
  public:
-  MockCanceledAfterSentPluginProcessHostClient(
+  explicit MockCanceledAfterSentPluginProcessHostClient(
       ResourceContext* context)
       : MockCanceledBeforeSentPluginProcessHostClient(context),
         on_sent_plugin_channel_request_called_(false) {}