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

gpu/command_buffer/client/share_group.cc

Index: gpu/command_buffer/client/share_group.cc
diff --git a/gpu/command_buffer/client/share_group.cc b/gpu/command_buffer/client/share_group.cc
index 041d79d1c4f3a5da8dcab3e18af2bad1f83f86f9..6f1cb214d7254332018a197c34a65baa9186148c 100644
--- a/gpu/command_buffer/client/share_group.cc
+++ b/gpu/command_buffer/client/share_group.cc
@@ -117,7 +117,7 @@ class NonReusedIdHandler : public IdHandlerInterface {
 // An id handler for shared ids.
 class SharedIdHandler : public IdHandlerInterface {
  public:
-  SharedIdHandler(
+  explicit SharedIdHandler(
       id_namespaces::IdNamespaces id_namespace)
       : id_namespace_(id_namespace) {
   }
@@ -158,7 +158,7 @@ class SharedIdHandler : public IdHandlerInterface {
 
 class ThreadSafeIdHandlerWrapper : public IdHandlerInterface {
  public:
-  ThreadSafeIdHandlerWrapper(IdHandlerInterface* id_handler)
+  explicit ThreadSafeIdHandlerWrapper(IdHandlerInterface* id_handler)
       : id_handler_(id_handler) {
   }
   virtual ~ThreadSafeIdHandlerWrapper() { }