Sampling Heap Profiler: Optimize fast path of the allocation hooks.

Do not create Sample object ahead.
Moved all the hooks into the SamplingNativeHeapProfiler class to improve
code readability.

BUG=803276

Change-Id: I88a920c338d19fc89689c3f797d2c002a3d976cb
Reviewed-on: https://chromium-review.googlesource.com/879595
Commit-Queue: Alexei Filippov <alph@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Reviewed-by: Primiano Tucci <primiano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532028}

third_party/WebKit/Source/platform/memory_profiler/SamplingNativeHeapProfiler.h

@@ -8,6 +8,7 @@
 #include <unordered_map>
 #include <vector>
 
+#include "base/allocator/allocator_shim.h"
 #include "base/atomicops.h"
 #include "base/macros.h"
 #include "base/synchronization/lock.h"
@@ -23,12 +24,19 @@ namespace blink {
 
 class PLATFORM_EXPORT SamplingNativeHeapProfiler {
  public:
-  struct Sample {
+  class Sample {
+   public:
     size_t size;
     size_t count;
+    std::vector<void*> stack;
+
+   private:
+    friend class SamplingNativeHeapProfiler;
+
+    Sample(size_t, size_t count, unsigned ordinal, unsigned offset);
+
     uint32_t ordinal;
     uint32_t offset;
-    std::vector<void*> stack;
   };
 
   SamplingNativeHeapProfiler() = default;
@@ -42,25 +50,64 @@ class PLATFORM_EXPORT SamplingNativeHeapProfiler {
 
   static SamplingNativeHeapProfiler* GetInstance();
 
-  static inline bool CreateAllocSample(size_t, Sample*);
-  void* RecordAlloc(Sample&,
+ private:
+  static void InstallAllocatorHooksOnce();
+  static bool InstallAllocatorHooks();
+  static size_t GetNextSampleInterval(size_t base_interval);
+
+  static inline bool ShouldRecordSample(size_t, size_t* accumulated);
+  void* RecordAlloc(size_t total_allocated,
+                    size_t allocation_size,
                     void* address,
                     uint32_t offset,
                     unsigned skip_frames,
                     bool preserve_data = false);
   void* RecordFree(void* address);
-
- private:
-  static void InstallAllocatorHooksOnce();
-  static bool InstallAllocatorHooks();
-  static intptr_t GetNextSampleInterval(uint64_t base_interval);
-
   void RecordStackTrace(Sample*, unsigned skip_frames);
 
+  static void* AllocFn(const base::allocator::AllocatorDispatch* self,
+                       size_t,
+                       void* context);
+  static void* AllocZeroInitializedFn(
+      const base::allocator::AllocatorDispatch* self,
+      size_t n,
+      size_t,
+      void* context);
+  static void* AllocAlignedFn(const base::allocator::AllocatorDispatch* self,
+                              size_t alignment,
+                              size_t,
+                              void* context);
+  static void* ReallocFn(const base::allocator::AllocatorDispatch* self,
+                         void* address,
+                         size_t,
+                         void* context);
+  static void FreeFn(const base::allocator::AllocatorDispatch* self,
+                     void* address,
+                     void* context);
+  static size_t GetSizeEstimateFn(
+      const base::allocator::AllocatorDispatch* self,
+      void* address,
+      void* context);
+  static unsigned BatchMallocFn(const base::allocator::AllocatorDispatch* self,
+                                size_t,
+                                void** results,
+                                unsigned num_requested,
+                                void* context);
+  static void BatchFreeFn(const base::allocator::AllocatorDispatch* self,
+                          void** to_be_freed,
+                          unsigned num_to_be_freed,
+                          void* context);
+  static void FreeDefiniteSizeFn(const base::allocator::AllocatorDispatch* self,
+                                 void* ptr,
+                                 size_t,
+                                 void* context);
+
   base::ThreadLocalBoolean entered_;
   base::Lock mutex_;
   std::unordered_map<void*, Sample> samples_;
 
+  static base::allocator::AllocatorDispatch allocator_dispatch_;
+
   friend struct base::DefaultSingletonTraits<SamplingNativeHeapProfiler>;
 
   DISALLOW_COPY_AND_ASSIGN(SamplingNativeHeapProfiler);