Add fixed raster scale use counter histograms.

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 223 matching lines @@
       output_is_secure_(false),
       animation_host_(),
       rendering_stats_instrumentation_(rendering_stats_instrumentation),
       micro_benchmark_controller_(this),
       shared_bitmap_manager_(shared_bitmap_manager),
       gpu_memory_buffer_manager_(gpu_memory_buffer_manager),
       task_graph_runner_(task_graph_runner),
       id_(id),
       requires_high_res_to_draw_(false),
       is_likely_to_require_a_draw_(false),
-      mutator_(nullptr) {
+      mutator_(nullptr),
+      has_fixed_raster_scale_blurry_content_(false) {
   animation_host_ = AnimationHost::Create(ThreadInstance::IMPL);
   animation_host_->SetMutatorHostClient(this);
   animation_host_->SetSupportsScrollAnimations(SupportsImplScrolling());
 
   DCHECK(task_runner_provider_->IsImplThread());
   DidVisibilityChange(this, visible_);
 
   SetDebugState(settings.initial_debug_state);
 
   // LTHI always has an active tree.
@@ skipping 92 matching lines @@
   if (CommitToActiveTree())
     Animate();
   else
     AnimatePendingTreeAfterCommit();
 
   // LayerTreeHost may have changed the GPU rasterization flags state, which
   // may require an update of the tree resources.
   UpdateTreeResourcesForGpuRasterizationIfNeeded();
   sync_tree()->set_needs_update_draw_properties();
 
+  // Advance the attempted scale change history before updaring draw properties.

[danakj, 2016/05/10 22:05:30]

updating

[vmpstr, 2016/05/13 00:13:34]

Done.

+  fixed_raster_scale_attempted_scale_change_history_ <<= 1;
+
   // We need an update immediately post-commit to have the opportunity to create
   // tilings.  Because invalidations may be coming from the main thread, it's
   // safe to do an update for lcd text at this point and see if lcd text needs
   // to be disabled on any layers.
   bool update_lcd_text = true;
   sync_tree()->UpdateDrawProperties(update_lcd_text);
   // Start working on newly created tiles immediately if needed.
   // TODO(vmpstr): Investigate always having PrepareTiles issue
   // NotifyReadyToActivate, instead of handling it here.
   bool did_prepare_tiles = PrepareTiles();
@@ skipping 3594 matching lines @@
   // Supported in threaded mode.
   return task_runner_provider_->HasImplThread();
 }
 
 bool LayerTreeHostImpl::CommitToActiveTree() const {
   // In single threaded mode we skip the pending tree and commit directly to the
   // active tree.
   return !task_runner_provider_->HasImplThread();
 }
 
+bool LayerTreeHostImpl::HasFixedRasterScalePotentialPerformanceRegression()
+    const {
+  return fixed_raster_scale_attempted_scale_change_history_.count() >=
+         kFixedRasterScaleAttemptedScaleChangeThreshold;
+}
+
+void LayerTreeHostImpl::SetFixedRasterScaleAttemptedToChangeScale() {
+  fixed_raster_scale_attempted_scale_change_history_.set(0);
+}
+
 }  // namespace cc