Remove unused trace sampling states

R=ojan@chromium.org

Review URL: https://codereview.chromium.org/893503002

engine/core/Init.cpp

@@ -69,7 +69,6 @@ void CoreInitializer::init()
 
     QualifiedName::init();
     Partitions::init();
-    EventTracer::initialize();
 
     // Ensure that the main thread's thread-local data is initialized before
     // starting any worker threads.

engine/platform/EventTracer.cpp

@@ -40,29 +40,6 @@ namespace blink {
 
 COMPILE_ASSERT(sizeof(blink::Platform::TraceEventHandle) == sizeof(TraceEvent::TraceEventHandle), TraceEventHandle_types_must_be_compatible);
 
-// The dummy variable is needed to avoid a crash when someone updates the state variables
-// before EventTracer::initialize() is called.
-long dummyTraceSamplingState = 0;
-long* traceSamplingState[3] = {&dummyTraceSamplingState, &dummyTraceSamplingState, &dummyTraceSamplingState };
-
-void EventTracer::initialize()
-{
-    // current() might not exist in unit tests.
-    if (!blink::Platform::current())
-        return;
-
-    traceSamplingState[0] = blink::Platform::current()->getTraceSamplingState(0);
-    // FIXME: traceSamplingState[0] can be 0 in split-dll build. http://crbug.com/256965
-    if (!traceSamplingState[0])
-        traceSamplingState[0] = &dummyTraceSamplingState;
-    traceSamplingState[1] = blink::Platform::current()->getTraceSamplingState(1);
-    if (!traceSamplingState[1])
-        traceSamplingState[1] = &dummyTraceSamplingState;
-    traceSamplingState[2] = blink::Platform::current()->getTraceSamplingState(2);
-    if (!traceSamplingState[2])
-        traceSamplingState[2] = &dummyTraceSamplingState;
-}
-
 const unsigned char* EventTracer::getTraceCategoryEnabledFlag(const char* categoryName)
 {
     static const char* dummyCategoryEnabledFlag = "*";

engine/platform/EventTracer.h

@@ -50,12 +50,8 @@ public:
 
 }
 
-// FIXME: Make these global variables thread-safe. Make a value update atomic.
-PLATFORM_EXPORT extern long* traceSamplingState[3];
-
 class PLATFORM_EXPORT EventTracer {
 public:
-    static void initialize();
     static const unsigned char* getTraceCategoryEnabledFlag(const char*);
     static TraceEvent::TraceEventHandle addTraceEvent(char phase,
         const unsigned char* categoryEnabledFlag,

engine/platform/testing/RunAllTests.cpp

@@ -54,7 +54,6 @@ int main(int argc, char** argv)
     blink::TestingPlatformSupport platform(platformConfig);
 
     blink::Partitions::init();
-    blink::EventTracer::initialize();
     int result = base::RunUnitTestsUsingBaseTestSuite(argc, argv);
     blink::Partitions::shutdown();
     return result;

engine/public/platform/Platform.h

@@ -234,14 +234,6 @@ public:
     // addTraceEvent is expected to be called by the trace event macros.
     virtual const unsigned char* getTraceCategoryEnabledFlag(const char* categoryName) { return 0; }
 
-    typedef long int TraceEventAPIAtomicWord;
-
-    // Get a pointer to a global state of the given thread. An embedder is
-    // expected to update the global state as the state of the embedder changes.
-    // A sampling thread in the Chromium side reads the global state periodically
-    // and reflects the sampling profiled results into about:tracing.
-    virtual TraceEventAPIAtomicWord* getTraceSamplingState(const unsigned bucketName) { return 0; }
-
     typedef uint64_t TraceEventHandle;
 
     // Add a trace event to the platform tracing system. Depending on the actual

viewer/platform/platform_impl.cc

@@ -128,20 +128,6 @@ const unsigned char* PlatformImpl::getTraceCategoryEnabledFlag(
   return TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(category_group);
 }
 
-long* PlatformImpl::getTraceSamplingState(const unsigned thread_bucket) {
-  switch (thread_bucket) {
-    case 0:
-      return reinterpret_cast<long*>(&TRACE_EVENT_API_THREAD_BUCKET(0));
-    case 1:
-      return reinterpret_cast<long*>(&TRACE_EVENT_API_THREAD_BUCKET(1));
-    case 2:
-      return reinterpret_cast<long*>(&TRACE_EVENT_API_THREAD_BUCKET(2));
-    default:
-      NOTREACHED() << "Unknown thread bucket type.";
-  }
-  return NULL;
-}
-
 COMPILE_ASSERT(
     sizeof(blink::Platform::TraceEventHandle) ==
         sizeof(base::debug::TraceEventHandle),

viewer/platform/platform_impl.h

@@ -34,7 +34,6 @@ class PlatformImpl : public blink::Platform {
   virtual blink::WebURLError cancelledError(const blink::WebURL& url) const;
   virtual const unsigned char* getTraceCategoryEnabledFlag(
       const char* category_name);
-  virtual long* getTraceSamplingState(const unsigned thread_bucket);
   virtual TraceEventHandle addTraceEvent(
       char phase,
       const unsigned char* category_group_enabled,