Instrument ContextCacheController::OnIdle for postmortem reports

cc/output/context_cache_controller.cc

Index: cc/output/context_cache_controller.cc
diff --git a/cc/output/context_cache_controller.cc b/cc/output/context_cache_controller.cc
index 79e85b3e0336146e41e82aaaf4d0463e21d2e141..096242b94572ca52d395a7348a6e783926f8bc68 100644
--- a/cc/output/context_cache_controller.cc
+++ b/cc/output/context_cache_controller.cc
@@ -5,6 +5,7 @@
 #include "cc/output/context_cache_controller.h"
 
 #include "base/bind.h"
+#include "base/debug/activity_tracker.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/synchronization/lock.h"
@@ -158,8 +159,14 @@ void ContextCacheController::OnIdle(uint32_t idle_generation) {
     return;
   }
 
-  if (gr_context_)
+  if (gr_context_) {
+    // TODO(manzagop): remove ScopedActivity once crbug.com/703342 is fixed.
+    const uint32_t kActivityId =
+        0x0e38f5d0;  // SHA1(ContextCacheController::OnIdle)
+    base::debug::ScopedActivity activity_free(0, kActivityId, 0);
+
     gr_context_->freeGpuResources();
+  }
 
   // Toggle SetAggressivelyFreeResources to drop command buffer data.
   context_support_->SetAggressivelyFreeResources(true);