Add VLOG(collector) to reduce log spam

VLOG(gc) is enabled from AndroidRuntime, using it too much produces
log spam.

Bug: 22858531

(cherry picked from commit a6e1c126299586932ecd3c1133a55a6f8e1107fc)

Change-Id: If60902a8d7855cdabd80208b9b385ce4ba4d9e5f
diff --git a/runtime/base/logging.h b/runtime/base/logging.h
index de46b0c..8aaeaac 100644
--- a/runtime/base/logging.h
+++ b/runtime/base/logging.h
@@ -37,6 +37,7 @@
 // and the "-verbose:" command line argument.
 struct LogVerbosity {
   bool class_linker;  // Enabled with "-verbose:class".
+  bool collector;
   bool compiler;
   bool deopt;
   bool gc;
diff --git a/runtime/gc/collector/immune_spaces.cc b/runtime/gc/collector/immune_spaces.cc
index 0862ff0..26da4ca 100644
--- a/runtime/gc/collector/immune_spaces.cc
+++ b/runtime/gc/collector/immune_spaces.cc
@@ -77,8 +77,8 @@
   }
   largest_immune_region_.SetBegin(reinterpret_cast<mirror::Object*>(best_begin));
   largest_immune_region_.SetEnd(reinterpret_cast<mirror::Object*>(best_end));
-  VLOG(gc) << "Immune region " << largest_immune_region_.Begin() << "-"
-           << largest_immune_region_.End();
+  VLOG(collector) << "Immune region " << largest_immune_region_.Begin() << "-"
+                  << largest_immune_region_.End();
 }
 
 void ImmuneSpaces::AddSpace(space::ContinuousSpace* space) {
diff --git a/runtime/parsed_options.cc b/runtime/parsed_options.cc
index f9d916a..d64aa43 100644
--- a/runtime/parsed_options.cc
+++ b/runtime/parsed_options.cc
@@ -394,6 +394,7 @@
 // Intended for local changes only.
 static void MaybeOverrideVerbosity() {
   //  gLogVerbosity.class_linker = true;  // TODO: don't check this in!
+  //  gLogVerbosity.collector = true;  // TODO: don't check this in!
   //  gLogVerbosity.compiler = true;  // TODO: don't check this in!
   //  gLogVerbosity.deopt = true;  // TODO: don't check this in!
   //  gLogVerbosity.gc = true;  // TODO: don't check this in!