[scheduler] Use Finch to control background throttling.

content/browser/renderer_host/render_view_host_impl.cc

Index: content/browser/renderer_host/render_view_host_impl.cc
diff --git a/content/browser/renderer_host/render_view_host_impl.cc b/content/browser/renderer_host/render_view_host_impl.cc
index 463b5d1e0432dda6abf647fba21089dde042d18f..554b2f6c1e3bb0b7c3e57d2e79e9df70bb0a0b8d 100644
--- a/content/browser/renderer_host/render_view_host_impl.cc
+++ b/content/browser/renderer_host/render_view_host_impl.cc
@@ -19,6 +19,7 @@
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/stl_util.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/sys_info.h"
@@ -27,6 +28,7 @@
 #include "base/values.h"
 #include "build/build_config.h"
 #include "cc/base/switches.h"
+#include "components/variations/variations_associated_data.h"
 #include "content/browser/bad_message.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/dom_storage/session_storage_namespace_impl.h"
@@ -413,6 +415,23 @@ void RenderViewHostImpl::SyncRendererPrefs() {
   Send(new ViewMsg_SetRendererPrefs(GetRoutingID(), renderer_preferences));
 }
 
+namespace {
+
+void MaybeSetParameterFromMap(
+    const std::map<std::string, std::string>& settings,

[alex clarke (OOO till 29th), 2016/11/02 17:53:48]

Are you aware of base::DictionaryValue?

[altimin, 2016/11/02 21:10:01]

Could you clarify this, please?
I'm aware of base::DictionaryValue, but Finch API returns map of strings.

[alex clarke (OOO till 29th), 2016/11/03 15:10:06]

I was thinking this rather steps on the toes of base::DictionaryValue, however
you are right that the API is at 'fault'.

+    const std::string& setting_name,
+    float* value) {
+  auto find_it = settings.find(setting_name);

[alex clarke (OOO till 29th), 2016/11/02 17:53:48]

const auto

[altimin, 2016/11/02 21:10:01]

Done.

+  if (find_it == settings.end())
+    return;
+  double parsed_value;
+  if (!base::StringToDouble(find_it->second, &parsed_value))
+    return;
+  *value = parsed_value;
+}
+
+}  // namespace
+
 WebPreferences RenderViewHostImpl::ComputeWebkitPrefs() {
   TRACE_EVENT0("browser", "RenderViewHostImpl::GetWebkitPrefs");
   WebPreferences prefs;
@@ -572,6 +591,20 @@ WebPreferences RenderViewHostImpl::ComputeWebkitPrefs() {
   if (delegate_ && delegate_->HideDownloadUI())
     prefs.hide_download_ui = true;
 
+  std::map<std::string, std::string> expensive_background_throttling_prefs;
+  variations::GetVariationParamsByFeature(
+      features::kExpensiveBackgroundTimerThrottling,
+      &expensive_background_throttling_prefs);
+  MaybeSetParameterFromMap(expensive_background_throttling_prefs, "cpu_budget",
+                           &prefs.expensive_background_throttling_cpu_budget);
+  MaybeSetParameterFromMap(
+      expensive_background_throttling_prefs, "initial_budget",
+      &prefs.expensive_background_throttling_initial_budget);
+  MaybeSetParameterFromMap(expensive_background_throttling_prefs, "max_budget",
+                           &prefs.expensive_background_throttling_max_budget);
+  MaybeSetParameterFromMap(expensive_background_throttling_prefs, "max_delay",
+                           &prefs.expensive_background_throttling_max_delay);
+
   GetContentClient()->browser()->OverrideWebkitPrefs(this, &prefs);
   return prefs;
 }