Show a warning message if the cache might not be cleared between runs.

BUG=None.
TEST=Unit tests pass.

Review URL: http://codereview.chromium.org/2819037

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@51541 0039d316-1c4b-4281-b951-d872f2087c98

chrome/common/extensions/docs/examples/extensions/benchmark/background.html

@@ -322,6 +322,20 @@ chrome.extension.onConnect.addListener(function(port) {
 });
 
 function run() {
+  if (window.clearCache) {
+    // Show a warning if we will try to clear the cache between runs
+    // but will also be reusing the same WebKit instance (i.e. Chrome
+    // is in single-process mode, or 'Use New Tabs' is turned off)
+    // because the WebKit cache might not get completely cleared between runs.
+    if (chrome.benchmarking.isSingleProcess()) {
+      alert("Warning: the WebKit cache may not be cleared correctly " +
+            "between runs because Chrome is running in single-process mode.");
+    } else if (!window.useNewTabs) {
+      alert("Warning: the WebKit cache may not be cleared correctly " +
+            "between runs because 'Use New Tabs Per Page' is turned off.");
+    }
+  }
+
   var urls = testUrl.split(",");
   for (var i = 0; i < urls.length; i++) {
     var benchmark = new Benchmark();

chrome/renderer/renderer_glue.cc

@@ -15,6 +15,7 @@
 #include "app/clipboard/clipboard.h"
 #include "app/clipboard/scoped_clipboard_writer.h"
 #include "app/resource_bundle.h"
+#include "base/command_line.h"
 #include "base/file_version_info.h"
 #include "base/ref_counted.h"
 #include "base/string_util.h"
@@ -281,4 +282,8 @@ std::string GetProductVersion() {
   return product;
 }
 
+bool IsSingleProcess() {
+  return CommandLine::ForCurrentProcess()->HasSwitch(switches::kSingleProcess);
+}
+
 }  // namespace webkit_glue

webkit/extensions/v8/benchmarking_extension.cc

@@ -2,6 +2,7 @@
 // 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/stats_table.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebCache.h"
 #include "webkit/extensions/v8/benchmarking_extension.h"
@@ -35,6 +36,10 @@ class BenchmarkingWrapper : public v8::Extension {
         "  native function GetCounter();"
         "  return GetCounter(name);"
         "};"
+        "chrome.benchmarking.isSingleProcess = function() {"
+        "  native function IsSingleProcess();"
+        "  return IsSingleProcess();"
+        "};"
         ) {}
 
   virtual v8::Handle<v8::FunctionTemplate> GetNativeFunction(
@@ -45,6 +50,8 @@ class BenchmarkingWrapper : public v8::Extension {
       return v8::FunctionTemplate::New(ClearCache);
     } else if (name->Equals(v8::String::New("GetCounter"))) {
       return v8::FunctionTemplate::New(GetCounter);
+    } else if (name->Equals(v8::String::New("IsSingleProcess"))) {
+      return v8::FunctionTemplate::New(IsSingleProcess);
     }
     return v8::Handle<v8::FunctionTemplate>();
   }
@@ -73,6 +80,10 @@ class BenchmarkingWrapper : public v8::Extension {
     int counter = StatsTable::current()->GetCounterValue(name);
     return v8::Integer::New(counter);
   }
+
+  static v8::Handle<v8::Value> IsSingleProcess(const v8::Arguments& args) {
+    return v8::Boolean::New(webkit_glue::IsSingleProcess());
+  }
 };
 
 v8::Extension* BenchmarkingExtension::Get() {

webkit/glue/webkit_glue.h

@@ -248,6 +248,9 @@ void ClearCache();
 // Returns the product version.  E.g., Chrome/4.1.333.0
 std::string GetProductVersion();
 
+// Returns true if the embedder is running in single process mode.
+bool IsSingleProcess();
+
 // ---- END FUNCTIONS IMPLEMENTED BY EMBEDDER ---------------------------------
 
 

webkit/support/webkit_support_glue.cc

@@ -68,4 +68,8 @@ bool DownloadUrl(const std::string& url, HWND caller_window) {
 }
 #endif
 
+bool IsSingleProcess() {
+  return true;
+}
+
 }  // namespace webkit_glue

webkit/tools/test_shell/test_shell.cc

@@ -809,4 +809,8 @@ std::string GetProductVersion() {
   return std::string("Chrome/0.0.0.0");
 }
 
+bool IsSingleProcess() {
+  return true;
+}
+
 }  // namespace webkit_glue