Plugin Power Saver: Improve Poster behavior for essential plugins.

chrome/renderer/plugins/power_saver_info.cc

Index: chrome/renderer/plugins/power_saver_info.cc
diff --git a/chrome/renderer/plugins/power_saver_info.cc b/chrome/renderer/plugins/power_saver_info.cc
new file mode 100644
index 0000000000000000000000000000000000000000..600a29c123cafad2486501efb1451be1c29b880d
--- /dev/null
+++ b/chrome/renderer/plugins/power_saver_info.cc
@@ -0,0 +1,124 @@
+// Copyright 2015 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 "base/command_line.h"
+#include "base/metrics/histogram_macros.h"
+#include "base/strings/utf_string_conversions.h"
+#include "chrome/renderer/plugins/power_saver_info.h"
+#include "content/public/common/content_constants.h"
+#include "content/public/common/content_switches.h"
+#include "content/public/common/webplugininfo.h"
+#include "content/public/renderer/render_frame.h"
+#include "third_party/WebKit/public/platform/WebSecurityOrigin.h"
+#include "third_party/WebKit/public/web/WebLocalFrame.h"
+#include "third_party/WebKit/public/web/WebPluginParams.h"
+#include "url/origin.h"
+
+namespace {
+
+// Presence of the poster param within plugin object tags.
+// These numeric values are used in UMA logs; do not change them.
+enum PosterParamPresence {
+  POSTER_PRESENCE_NO_PARAM_PPS_DISABLED = 0,
+  POSTER_PRESENCE_NO_PARAM_PPS_ENABLED = 1,
+  POSTER_PRESENCE_PARAM_EXISTS_PPS_DISABLED = 2,
+  POSTER_PRESENCE_PARAM_EXISTS_PPS_ENABLED = 3,
+  POSTER_PRESENCE_NUM_ITEMS
+};
+
+const char kPluginPowerSaverPosterParamPresenceHistogram[] =
+    "Plugin.PowerSaver.PosterParamPresence";
+
+void RecordPosterParamPresence(PosterParamPresence presence) {
+  UMA_HISTOGRAM_ENUMERATION(kPluginPowerSaverPosterParamPresenceHistogram,
+                            presence, POSTER_PRESENCE_NUM_ITEMS);
+}
+
+void TrackPosterParamPresence(const blink::WebPluginParams& params,
+                              bool power_saver_enabled) {
+  DCHECK_EQ(params.attributeNames.size(), params.attributeValues.size());
+
+  for (size_t i = 0; i < params.attributeNames.size(); ++i) {
+    if (params.attributeNames[i].utf8() == "poster") {
+      RecordPosterParamPresence(
+          power_saver_enabled ? POSTER_PRESENCE_PARAM_EXISTS_PPS_ENABLED
+                              : POSTER_PRESENCE_PARAM_EXISTS_PPS_DISABLED);
+      return;
+    }
+  }
+
+  RecordPosterParamPresence(power_saver_enabled
+                                ? POSTER_PRESENCE_NO_PARAM_PPS_ENABLED
+                                : POSTER_PRESENCE_NO_PARAM_PPS_DISABLED);
+}
+
+std::string GetPluginInstancePosterAttribute(
+    const blink::WebPluginParams& params) {
+  DCHECK_EQ(params.attributeNames.size(), params.attributeValues.size());
+
+  for (size_t i = 0; i < params.attributeNames.size(); ++i) {
+    if (params.attributeNames[i].utf8() == "poster" &&
+        !params.attributeValues[i].isEmpty()) {
+      return params.attributeValues[i].utf8();
+    }
+  }
+  return std::string();
+}
+
+}  // namespace
+
+PowerSaverInfo::PowerSaverInfo()
+    : power_saver_enabled(false), blocked_for_background_tab(false) {}
+
+PowerSaverInfo PowerSaverInfo::Get(content::RenderFrame* render_frame,
+                                   bool power_saver_setting_on,
+                                   const blink::WebPluginParams& params,
+                                   const content::WebPluginInfo& plugin_info,
+                                   const GURL& document_url) {
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  std::string override_for_testing = command_line->GetSwitchValueASCII(
+      switches::kOverridePluginPowerSaverForTesting);
+
+  // This feature has only been tested thoroughly with Flash thus far.
+  // It is also enabled for the Power Saver test plugin for browser tests.
+  bool is_flash =
+      plugin_info.name == base::ASCIIToUTF16(content::kFlashPluginName);
+  bool can_throttle_plugin_type =
+      is_flash || override_for_testing == "ignore-list";
+
+  PowerSaverInfo info;
+  info.power_saver_enabled =
+      override_for_testing == "always" ||
+      (power_saver_setting_on && can_throttle_plugin_type);
+
+  if (info.power_saver_enabled) {
+    // Even if we disable PPS in the next block because content is same-origin,
+    // it should still be eligible for background tab deferral if PPS is on.
+    info.blocked_for_background_tab = render_frame->IsHidden();
+
+    auto status = render_frame->GetPeripheralContentStatus(
+        render_frame->GetWebFrame()->top()->securityOrigin(),
+        url::Origin(params.url), gfx::Size());
+
+    // Early-exit from the whole Power Saver system if the content is
+    // same-origin or whitelisted-origin. We ignore the other possibilities,
+    // because we don't know the unobscured size of the plugin content yet.
+    //
+    // Once the plugin is loaded, the peripheral content status is re-tested
+    // with the actual unobscured plugin size.
+    if (status == content::RenderFrame::CONTENT_STATUS_ESSENTIAL_SAME_ORIGIN ||
+        status == content::RenderFrame::
+                      CONTENT_STATUS_ESSENTIAL_CROSS_ORIGIN_WHITELISTED) {
+      info.power_saver_enabled = false;
+    } else {
+      info.poster_attribute = GetPluginInstancePosterAttribute(params);
+      info.base_url = document_url;
+    }
+  }
+
+  if (is_flash)
+    TrackPosterParamPresence(params, info.power_saver_enabled);
+
+  return info;
+}