Fix cpplint runtime/explicit issues

Change-Id: I352ba0b427f1ff9b22887693952b180eae0839ba
diff --git a/runtime/gc/accounting/heap_bitmap.h b/runtime/gc/accounting/heap_bitmap.h
index a12809e..f4b725c 100644
--- a/runtime/gc/accounting/heap_bitmap.h
+++ b/runtime/gc/accounting/heap_bitmap.h
@@ -103,8 +103,7 @@
   void ReplaceObjectSet(SpaceSetMap* old_set, SpaceSetMap* new_set)
       EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_);
 
-  HeapBitmap(Heap* heap) : heap_(heap) {
-  }
+  explicit HeapBitmap(Heap* heap) : heap_(heap) {}
 
  private:
 
diff --git a/runtime/gc/accounting/mod_union_table-inl.h b/runtime/gc/accounting/mod_union_table-inl.h
index 32ac95f..9ea74d4 100644
--- a/runtime/gc/accounting/mod_union_table-inl.h
+++ b/runtime/gc/accounting/mod_union_table-inl.h
@@ -28,8 +28,7 @@
 // A mod-union table to record image references to the Zygote and alloc space.
 class ModUnionTableToZygoteAllocspace : public ModUnionTableReferenceCache {
 public:
-  ModUnionTableToZygoteAllocspace(Heap* heap) : ModUnionTableReferenceCache(heap) {
-  }
+  explicit ModUnionTableToZygoteAllocspace(Heap* heap) : ModUnionTableReferenceCache(heap) {}
 
   bool AddReference(const mirror::Object* /* obj */, const mirror::Object* ref) {
     const std::vector<space::ContinuousSpace*>& spaces = GetHeap()->GetContinuousSpaces();
@@ -48,8 +47,7 @@
 // A mod-union table to record Zygote references to the alloc space.
 class ModUnionTableToAllocspace : public ModUnionTableReferenceCache {
  public:
-  ModUnionTableToAllocspace(Heap* heap) : ModUnionTableReferenceCache(heap) {
-  }
+  explicit ModUnionTableToAllocspace(Heap* heap) : ModUnionTableReferenceCache(heap) {}
 
   bool AddReference(const mirror::Object* /* obj */, const mirror::Object* ref) {
     const std::vector<space::ContinuousSpace*>& spaces = GetHeap()->GetContinuousSpaces();
diff --git a/runtime/gc/accounting/mod_union_table.cc b/runtime/gc/accounting/mod_union_table.cc
index 05b68c4..aa02f82 100644
--- a/runtime/gc/accounting/mod_union_table.cc
+++ b/runtime/gc/accounting/mod_union_table.cc
@@ -117,8 +117,8 @@
 
 class ModUnionScanImageRootVisitor {
  public:
-  ModUnionScanImageRootVisitor(collector::MarkSweep* const mark_sweep) : mark_sweep_(mark_sweep) {
-  }
+  explicit ModUnionScanImageRootVisitor(collector::MarkSweep* const mark_sweep)
+      : mark_sweep_(mark_sweep) {}
 
   void operator ()(const Object* root) const
       EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
diff --git a/runtime/gc/accounting/mod_union_table.h b/runtime/gc/accounting/mod_union_table.h
index 5435625..d46281c 100644
--- a/runtime/gc/accounting/mod_union_table.h
+++ b/runtime/gc/accounting/mod_union_table.h
@@ -49,11 +49,9 @@
 // cleared between GC phases, reducing the number of dirty cards that need to be scanned.
 class ModUnionTable {
  public:
-  ModUnionTable(Heap* heap) : heap_(heap) {
-  }
+  explicit ModUnionTable(Heap* heap) : heap_(heap) {}
 
-  virtual ~ModUnionTable() {
-  }
+  virtual ~ModUnionTable() {}
 
   // Clear cards which map to a memory range of a space. This doesn't immediately update the
   // mod-union table, as updating the mod-union table may have an associated cost, such as
@@ -86,7 +84,7 @@
 // Reference caching implementation. Caches references pointing to alloc space(s) for each card.
 class ModUnionTableReferenceCache : public ModUnionTable {
  public:
-  ModUnionTableReferenceCache(Heap* heap) : ModUnionTable(heap) {}
+  explicit ModUnionTableReferenceCache(Heap* heap) : ModUnionTable(heap) {}
   virtual ~ModUnionTableReferenceCache() {}
 
   // Clear and store cards for a space.
@@ -122,7 +120,7 @@
 // Card caching implementation. Keeps track of which cards we cleared and only this information.
 class ModUnionTableCardCache : public ModUnionTable {
  public:
-  ModUnionTableCardCache(Heap* heap) : ModUnionTable(heap) {}
+  explicit ModUnionTableCardCache(Heap* heap) : ModUnionTable(heap) {}
   virtual ~ModUnionTableCardCache() {}
 
   // Clear and store cards for a space.
diff --git a/runtime/gc/accounting/space_bitmap.h b/runtime/gc/accounting/space_bitmap.h
index 32ab440..5a1bfe3 100644
--- a/runtime/gc/accounting/space_bitmap.h
+++ b/runtime/gc/accounting/space_bitmap.h
@@ -244,7 +244,7 @@
     }
   }
 
-  SpaceSetMap(const std::string& name) : name_(name) {}
+  explicit SpaceSetMap(const std::string& name) : name_(name) {}
   ~SpaceSetMap() {}
 
   Objects& GetObjects() {
diff --git a/runtime/gc/collector/mark_sweep.cc b/runtime/gc/collector/mark_sweep.cc
index 279796f..a5bad2f 100644
--- a/runtime/gc/collector/mark_sweep.cc
+++ b/runtime/gc/collector/mark_sweep.cc
@@ -70,8 +70,7 @@
 
 class SetFingerVisitor {
  public:
-  SetFingerVisitor(MarkSweep* const mark_sweep) : mark_sweep_(mark_sweep) {
-  }
+  explicit SetFingerVisitor(MarkSweep* const mark_sweep) : mark_sweep_(mark_sweep) {}
 
   void operator ()(void* finger) const {
     mark_sweep_->SetFinger(reinterpret_cast<Object*>(finger));
@@ -523,10 +522,7 @@
 
 class CheckObjectVisitor {
  public:
-  CheckObjectVisitor(MarkSweep* const mark_sweep)
-      : mark_sweep_(mark_sweep) {
-
-  }
+  explicit CheckObjectVisitor(MarkSweep* const mark_sweep) : mark_sweep_(mark_sweep) {}
 
   void operator ()(const Object* obj, const Object* ref, MemberOffset offset, bool is_static) const
       NO_THREAD_SAFETY_ANALYSIS {
@@ -566,8 +562,7 @@
 
 class ScanObjectVisitor {
  public:
-  ScanObjectVisitor(MarkSweep* const mark_sweep) : mark_sweep_(mark_sweep) {
-  }
+  explicit ScanObjectVisitor(MarkSweep* const mark_sweep) : mark_sweep_(mark_sweep) {}
 
   // TODO: Fixme when anotatalysis works with visitors.
   void operator ()(const Object* obj) const NO_THREAD_SAFETY_ANALYSIS {
@@ -612,8 +607,7 @@
 
 class CheckBitmapVisitor {
  public:
-  CheckBitmapVisitor(MarkSweep* mark_sweep) : mark_sweep_(mark_sweep) {
-  }
+  explicit CheckBitmapVisitor(MarkSweep* mark_sweep) : mark_sweep_(mark_sweep) {}
 
   void operator ()(const Object* obj) const NO_THREAD_SAFETY_ANALYSIS {
     if (kDebugLocking) {
@@ -805,9 +799,7 @@
 
 class CheckpointMarkThreadRoots : public Closure {
  public:
-  CheckpointMarkThreadRoots(MarkSweep* mark_sweep) : mark_sweep_(mark_sweep) {
-
-  }
+  explicit CheckpointMarkThreadRoots(MarkSweep* mark_sweep) : mark_sweep_(mark_sweep) {}
 
   virtual void Run(Thread* thread) NO_THREAD_SAFETY_ANALYSIS {
     // Note: self is not necessarily equal to thread since thread may be suspended.
@@ -1086,8 +1078,7 @@
 
 class MarkObjectVisitor {
  public:
-  MarkObjectVisitor(MarkSweep* const mark_sweep) : mark_sweep_(mark_sweep) {
-  }
+  explicit MarkObjectVisitor(MarkSweep* const mark_sweep) : mark_sweep_(mark_sweep) {}
 
   // TODO: Fixme when anotatalysis works with visitors.
   void operator ()(const Object* /* obj */, const Object* ref, const MemberOffset& /* offset */,
@@ -1155,9 +1146,7 @@
 
   class MarkObjectParallelVisitor {
    public:
-    MarkObjectParallelVisitor(MarkStackChunk* chunk_task) : chunk_task_(chunk_task) {
-
-    }
+    explicit MarkObjectParallelVisitor(MarkStackChunk* chunk_task) : chunk_task_(chunk_task) {}
 
     void operator ()(const Object* /* obj */, const Object* ref,
                      const MemberOffset& /* offset */, bool /* is_static */) const {
diff --git a/runtime/gc/heap.cc b/runtime/gc/heap.cc
index 53b8cd9..85b7bf0 100644
--- a/runtime/gc/heap.cc
+++ b/runtime/gc/heap.cc
@@ -1173,10 +1173,9 @@
 // Verify a reference from an object.
 class VerifyReferenceVisitor {
  public:
-  VerifyReferenceVisitor(Heap* heap)
+  explicit VerifyReferenceVisitor(Heap* heap)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_)
-      : heap_(heap), failed_(false) {
-  }
+      : heap_(heap), failed_(false) {}
 
   bool Failed() const {
     return failed_;
@@ -1263,8 +1262,7 @@
 // Verify all references within an object, for use with HeapBitmap::Visit.
 class VerifyObjectVisitor {
  public:
-  VerifyObjectVisitor(Heap* heap) : heap_(heap), failed_(false) {
-  }
+  explicit VerifyObjectVisitor(Heap* heap) : heap_(heap), failed_(false) {}
 
   void operator ()(const mirror::Object* obj) const
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_) {
@@ -1376,11 +1374,9 @@
 
 class VerifyLiveStackReferences {
  public:
-  VerifyLiveStackReferences(Heap* heap)
+  explicit VerifyLiveStackReferences(Heap* heap)
       : heap_(heap),
-        failed_(false) {
-
-  }
+        failed_(false) {}
 
   void operator ()(const mirror::Object* obj) const
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_) {
diff --git a/runtime/gc/space/large_object_space.h b/runtime/gc/space/large_object_space.h
index 74d9cca..db845db 100644
--- a/runtime/gc/space/large_object_space.h
+++ b/runtime/gc/space/large_object_space.h
@@ -61,7 +61,7 @@
 
  protected:
 
-  LargeObjectSpace(const std::string& name);
+  explicit LargeObjectSpace(const std::string& name);
 
   // Approximate number of bytes which have been allocated into the space.
   size_t num_bytes_allocated_;
@@ -91,7 +91,7 @@
   bool Contains(const mirror::Object* obj) const NO_THREAD_SAFETY_ANALYSIS;
 
 private:
-  LargeObjectMapSpace(const std::string& name);
+  explicit LargeObjectMapSpace(const std::string& name);
   virtual ~LargeObjectMapSpace() {}
 
   // Used to ensure mutual exclusion when the allocation spaces data structures are being modified.