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

content/gpu/gpu_child_thread.h

Index: content/gpu/gpu_child_thread.h
diff --git a/content/gpu/gpu_child_thread.h b/content/gpu/gpu_child_thread.h
index 65579ad9d3580127e747d0f69657c74122e7a821..9244a69e7c2b5d5a62844c1c20d23e2cc379e9a2 100644
--- a/content/gpu/gpu_child_thread.h
+++ b/content/gpu/gpu_child_thread.h
@@ -34,9 +34,9 @@ class GpuWatchdogThread;
 // commands to the GPU.
 class GpuChildThread : public ChildThread {
  public:
-  explicit GpuChildThread(GpuWatchdogThread* gpu_watchdog_thread,
-                          bool dead_on_arrival,
-                          const GPUInfo& gpu_info);
+  GpuChildThread(GpuWatchdogThread* gpu_watchdog_thread,
+                 bool dead_on_arrival,
+                 const GPUInfo& gpu_info);
 
   // For single-process mode.
   explicit GpuChildThread(const std::string& channel_id);