Remove Sparse Histograms from Blink Platform API.

content/child/blink_platform_impl.h

 // Copyright 2014 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.
 
 #ifndef CONTENT_CHILD_BLINK_PLATFORM_IMPL_H_
 #define CONTENT_CHILD_BLINK_PLATFORM_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 101 matching lines @@
   void decrementStatsCounter(const char* name) override;
   void incrementStatsCounter(const char* name) override;
   void histogramCustomCounts(const char* name,
                              int sample,
                              int min,
                              int max,
                              int bucket_count) override;
   void histogramEnumeration(const char* name,
                             int sample,
                             int boundary_value) override;
-  void histogramSparse(const char* name, int sample) override;
   void registerMemoryDumpProvider(blink::WebMemoryDumpProvider* wmdp,
                                   const char* name) override;
   void unregisterMemoryDumpProvider(
       blink::WebMemoryDumpProvider* wmdp) override;
   blink::WebProcessMemoryDump* createProcessMemoryDump() override;
   blink::Platform::WebMemoryAllocatorDumpGuid createWebMemoryAllocatorDumpGuid(
       const blink::WebString& guidStr) override;
   void addTraceLogEnabledStateObserver(
       blink::Platform::TraceLogEnabledStateObserver* observer) override;
   void removeTraceLogEnabledStateObserver(
@@ skipping 68 matching lines @@
   scoped_ptr<BackgroundSyncProvider> main_thread_sync_provider_;
 
   ApiKeyValidator api_key_validator_;
 
   scheduler::WebThreadBase* compositor_thread_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_BLINK_PLATFORM_IMPL_H_