Move purging from OnMemoryState to OnPurgeMemory() in cc/

cc/raster/staging_buffer_pool.cc

Index: cc/raster/staging_buffer_pool.cc
diff --git a/cc/raster/staging_buffer_pool.cc b/cc/raster/staging_buffer_pool.cc
index ef78e4d317e60f4a8f3b3b5ca1298a05446fb60d..2672879e037f3dc102d95b23dfcb4b47c31d3003 100644
--- a/cc/raster/staging_buffer_pool.cc
+++ b/cc/raster/staging_buffer_pool.cc
@@ -433,23 +433,18 @@ void StagingBufferPool::ReleaseBuffersNotUsedSince(base::TimeTicks time) {
 }
 
 void StagingBufferPool::OnMemoryStateChange(base::MemoryState state) {
-  switch (state) {
-    case base::MemoryState::NORMAL:
-      // TODO(tasak): go back to normal state.
-      break;
-    case base::MemoryState::THROTTLED:
-      // TODO(tasak): make the limits of this component's caches smaller to
-      // save memory usage.
-      break;
-    case base::MemoryState::SUSPENDED: {
-      base::AutoLock lock(lock_);
-      // Release all buffers, regardless of how recently they were used.
-      ReleaseBuffersNotUsedSince(base::TimeTicks() + base::TimeDelta::Max());
-    } break;
-    case base::MemoryState::UNKNOWN:
-      // NOT_REACHED.
-      break;
-  }
+  // TODO(bashi): We are going to separate purging from state changes and we
+  // shouldn't purge memory here (crbug.com/684287). Tentatively call
+  // OnPurgeMemory() so that we don't break existing experiments.
+  // (i.e. purge+suspend experiment)
+  if (state == base::MemoryState::SUSPENDED)
+    OnPurgeMemory();
+}
+
+void StagingBufferPool::OnPurgeMemory() {
+  base::AutoLock lock(lock_);
+  // Release all buffers, regardless of how recently they were used.
+  ReleaseBuffersNotUsedSince(base::TimeTicks() + base::TimeDelta::Max());
 }
 
 }  // namespace cc