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

content/common/gpu/gpu_memory_allocation.h

Index: content/common/gpu/gpu_memory_allocation.h
diff --git a/content/common/gpu/gpu_memory_allocation.h b/content/common/gpu/gpu_memory_allocation.h
index cade6df940e92d5af7133c684e642cca2a73832c..ef00d2018f593a4f88a084dea3e03478193070e9 100644
--- a/content/common/gpu/gpu_memory_allocation.h
+++ b/content/common/gpu/gpu_memory_allocation.h
@@ -51,7 +51,7 @@ struct GpuMemoryAllocationForRenderer {
         enforce_but_do_not_keep_as_policy(false) {
   }
 
-  GpuMemoryAllocationForRenderer(size_t bytes_limit_when_visible)
+  explicit GpuMemoryAllocationForRenderer(size_t bytes_limit_when_visible)
       : bytes_limit_when_visible(bytes_limit_when_visible),
         priority_cutoff_when_visible(kPriorityCutoffAllowEverything),
         bytes_limit_when_not_visible(0),
@@ -82,7 +82,7 @@ struct GpuMemoryAllocationForBrowser {
       : suggest_have_frontbuffer(false) {
   }
 
-  GpuMemoryAllocationForBrowser(bool suggest_have_frontbuffer)
+  explicit GpuMemoryAllocationForBrowser(bool suggest_have_frontbuffer)
       : suggest_have_frontbuffer(suggest_have_frontbuffer) {
   }