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

content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.h"
 
 #include "third_party/khronos/GLES2/gl2.h"
 #ifndef GL_GLEXT_PROTOTYPES
 #define GL_GLEXT_PROTOTYPES 1
 #endif
@@ skipping 80 matching lines @@
 base::LazyInstance<GLES2Initializer> g_gles2_initializer =
     LAZY_INSTANCE_INITIALIZER;
 
 ////////////////////////////////////////////////////////////////////////////////
 
 } // namespace anonymous
 
 class WebGraphicsContext3DErrorMessageCallback
     : public gpu::gles2::GLES2Implementation::ErrorMessageCallback {
  public:
-  WebGraphicsContext3DErrorMessageCallback(
+  explicit WebGraphicsContext3DErrorMessageCallback(
       WebGraphicsContext3DCommandBufferImpl* context)
       : graphics_context_(context) {
   }
 
   virtual void OnErrorMessage(const char* msg, int id) OVERRIDE;
 
  private:
   WebGraphicsContext3DCommandBufferImpl* graphics_context_;
 
   DISALLOW_COPY_AND_ASSIGN(WebGraphicsContext3DErrorMessageCallback);
@@ skipping 1602 matching lines @@
 
 void WebGraphicsContext3DCommandBufferImpl::OnErrorMessage(
     const std::string& message, int id) {
   if (error_message_callback_) {
     WebKit::WebString str = WebKit::WebString::fromUTF8(message.c_str());
     error_message_callback_->onErrorMessage(str, id);
   }
 }
 
 }  // namespace content