Use TimeTicks instead of clock() in gpu::CommandBufferHelper

clock() returns a processor time, which does not change while
a thread is sleeping. So, Flush() would be called less often
than you expected.

TimeTicks uses a monotonic timer so this would be a better
choice than Time because TimeTicks is not affected by host's
time settings.

BUG=264856
TEST=trybots

Review URL: https://codereview.chromium.org/381473004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@282593 0039d316-1c4b-4281-b951-d872f2087c98

gpu/command_buffer/client/cmd_buffer_helper.cc

@@ -7,6 +7,7 @@
 #include "gpu/command_buffer/client/cmd_buffer_helper.h"
 
 #include "base/logging.h"
+#include "base/time/time.h"
 #include "gpu/command_buffer/common/command_buffer.h"
 #include "gpu/command_buffer/common/trace_event.h"
 
@@ -28,7 +29,6 @@ CommandBufferHelper::CommandBufferHelper(CommandBuffer* command_buffer)
       usable_(true),
       context_lost_(false),
       flush_automatically_(true),
-      last_flush_time_(0),
       flush_generation_(0) {
 }
 
@@ -151,7 +151,7 @@ void CommandBufferHelper::Flush() {
     put_ = 0;
 
   if (usable() && last_put_sent_ != put_) {
-    last_flush_time_ = clock();
+    last_flush_time_ = base::TimeTicks::Now();
     last_put_sent_ = put_;
     command_buffer_->Flush(put_);
     ++flush_generation_;
@@ -161,9 +161,11 @@ void CommandBufferHelper::Flush() {
 
 #if defined(CMD_HELPER_PERIODIC_FLUSH_CHECK)
 void CommandBufferHelper::PeriodicFlushCheck() {
-  clock_t current_time = clock();
-  if (current_time - last_flush_time_ > kPeriodicFlushDelay * CLOCKS_PER_SEC)
+  base::TimeTicks current_time = base::TimeTicks::Now();
+  if (current_time - last_flush_time_ >
+      base::TimeDelta::FromMicroseconds(kPeriodicFlushDelayInMicroseconds)) {
     Flush();
+  }
 }
 #endif
 

gpu/command_buffer/client/cmd_buffer_helper.h

@@ -10,6 +10,7 @@
 #include <string.h>
 #include <time.h>
 
+#include "base/time/time.h"
 #include "gpu/command_buffer/common/cmd_buffer_common.h"
 #include "gpu/command_buffer/common/command_buffer.h"
 #include "gpu/command_buffer/common/constants.h"
@@ -20,7 +21,8 @@ namespace gpu {
 #if !defined(OS_ANDROID)
 #define CMD_HELPER_PERIODIC_FLUSH_CHECK
 const int kCommandsPerFlushCheck = 100;
-const float kPeriodicFlushDelay = 1.0f / (5.0f * 60.0f);
+const int kPeriodicFlushDelayInMicroseconds =
+    base::Time::kMicrosecondsPerSecond / (5 * 60);
 #endif
 
 const int kAutoFlushSmall = 16;  // 1/16 of the buffer
@@ -325,8 +327,7 @@ class GPU_EXPORT CommandBufferHelper {
   bool context_lost_;
   bool flush_automatically_;
 
-  // Using C runtime instead of base because this file cannot depend on base.
-  clock_t last_flush_time_;
+  base::TimeTicks last_flush_time_;
 
   // Incremented every time the helper flushes the command buffer.
   // Can be used to track when prior commands have been flushed.