Plugin Power Saver: Always mark 'tiny' plugins as essential.

content/renderer/pepper/plugin_power_saver_helper_impl.cc

 // Copyright 2014 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 "content/renderer/pepper/plugin_power_saver_helper_impl.h"
 
 #include "base/metrics/histogram.h"
 #include "base/strings/string_number_conversions.h"
 #include "content/common/frame_messages.h"
 #include "content/public/renderer/document_state.h"
@@ skipping 10 matching lines @@
 
 const char kPosterParamName[] = "poster";
 
 // Initial decision of the peripheral content decision.
 // These numeric values are used in UMA logs; do not change them.
 enum PeripheralHeuristicDecision {
   HEURISTIC_DECISION_PERIPHERAL = 0,
   HEURISTIC_DECISION_ESSENTIAL_SAME_ORIGIN = 1,
   HEURISTIC_DECISION_ESSENTIAL_CROSS_ORIGIN_BIG = 2,
   HEURISTIC_DECISION_ESSENTIAL_CROSS_ORIGIN_WHITELISTED = 3,
+  HEURISTIC_DECISION_ESSENTIAL_CROSS_ORIGIN_TINY = 4,
   HEURISTIC_DECISION_NUM_ITEMS
 };
 
 const char kPeripheralHeuristicHistogram[] =
     "Plugin.PowerSaver.PeripheralHeuristic";
 
 // Maximum dimensions plug-in content may have while still being considered
 // peripheral content. These match the sizes used by Safari.
 const int kPeripheralContentMaxWidth = 400;
 const int kPeripheralContentMaxHeight = 300;
 
+// Plug-in content below this size in height and width is considered "tiny".
+// Tiny content is never peripheral, as tiny plug-ins often serve a critical
+// purpose, and the user often cannot find and click to unthrottle it.
+const int kPeripheralContentTinySize = 5;
+
 void RecordDecisionMetric(PeripheralHeuristicDecision decision) {
   UMA_HISTOGRAM_ENUMERATION(kPeripheralHeuristicHistogram, decision,
                             HEURISTIC_DECISION_NUM_ITEMS);
 }
 
 const char kWebPluginParamHeight[] = "height";
 const char kWebPluginParamWidth[] = "width";
 
 // Returns true if valid non-negative height and width extracted.
 // When this returns false, |width| and |height| are set to undefined values.
@@ skipping 78 matching lines @@
 
 GURL PluginPowerSaverHelperImpl::GetPluginInstancePosterImage(
     const blink::WebPluginParams& params,
     const GURL& base_url) const {
   DCHECK_EQ(params.attributeNames.size(), params.attributeValues.size());
 
   GURL content_origin = GURL(params.url).GetOrigin();
   int width = 0;
   int height = 0;
 
-  bool cross_origin = false;
   if (!ExtractDimensions(params, &width, &height))
     return GURL();
 
-  if (!ShouldThrottleContent(content_origin, width, height, &cross_origin))
+  if (!ShouldThrottleContent(content_origin, width, height, nullptr))
     return GURL();
 
   for (size_t i = 0; i < params.attributeNames.size(); ++i) {
     if (params.attributeNames[i] == kPosterParamName) {
       std::string poster_value(params.attributeValues[i].utf8());
       if (!poster_value.empty())
         return base_url.Resolve(poster_value);
     }
   }
   return GURL();
 }
 
 void PluginPowerSaverHelperImpl::RegisterPeripheralPlugin(
     const GURL& content_origin,
     const base::Closure& unthrottle_callback) {
   peripheral_plugins_.push_back(
       PeripheralPlugin(content_origin, unthrottle_callback));
 }
 
 bool PluginPowerSaverHelperImpl::ShouldThrottleContent(
     const GURL& content_origin,
     int width,
     int height,
-    bool* cross_origin) const {
-  DCHECK(cross_origin);
-  *cross_origin = true;
+    bool* is_main_attraction) const {
+  DCHECK_EQ(content_origin.GetOrigin(), content_origin);
+  if (is_main_attraction)
+    *is_main_attraction = false;
 
   // TODO(alexmos): Update this to use the origin of the RemoteFrame when 426512
   // is fixed. For now, case 3 in the class level comment doesn't work in
   // --site-per-process mode.
   blink::WebFrame* main_frame =
       render_frame()->GetWebFrame()->view()->mainFrame();
   if (main_frame->isWebRemoteFrame()) {
     RecordDecisionMetric(HEURISTIC_DECISION_PERIPHERAL);
     return true;
   }
 
   // All same-origin plugin content is essential.
   GURL main_frame_origin = GURL(main_frame->document().url()).GetOrigin();
   if (content_origin == main_frame_origin) {
     RecordDecisionMetric(HEURISTIC_DECISION_ESSENTIAL_SAME_ORIGIN);
-    *cross_origin = false;
     return false;
   }
 
   // Whitelisted plugin origins are also essential.
   if (origin_whitelist_.count(content_origin)) {
     RecordDecisionMetric(HEURISTIC_DECISION_ESSENTIAL_CROSS_ORIGIN_WHITELISTED);
     return false;
   }
 
-  // Cross-origin plugin content is peripheral if smaller than a maximum size.
-  bool content_is_small = width < kPeripheralContentMaxWidth ||
-                          height < kPeripheralContentMaxHeight;
+  // Never mark tiny content as peripheral.
+  if (width <= kPeripheralContentTinySize &&
+      height <= kPeripheralContentTinySize) {
+    RecordDecisionMetric(HEURISTIC_DECISION_ESSENTIAL_CROSS_ORIGIN_TINY);
+    return false;
+  }
 
-  if (content_is_small)
-    RecordDecisionMetric(HEURISTIC_DECISION_PERIPHERAL);
-  else
+  // Plugin content large in both dimensions are the "main attraction".
+  if (width >= kPeripheralContentMaxWidth &&
+      height >= kPeripheralContentMaxHeight) {
     RecordDecisionMetric(HEURISTIC_DECISION_ESSENTIAL_CROSS_ORIGIN_BIG);
+    if (is_main_attraction)
+      *is_main_attraction = true;
+    return false;
+  }
 
-  return content_is_small;
+  RecordDecisionMetric(HEURISTIC_DECISION_PERIPHERAL);
+  return true;
 }
 
 void PluginPowerSaverHelperImpl::WhitelistContentOrigin(
     const GURL& content_origin) {
   DCHECK_EQ(content_origin.GetOrigin(), content_origin);
   if (origin_whitelist_.insert(content_origin).second) {
     Send(new FrameHostMsg_PluginContentOriginAllowed(
         render_frame()->GetRoutingID(), content_origin));
   }
 }
 
 }  // namespace content