Per-host V8 histograms.

content/renderer/render_thread_impl_unittest.cc

+// Copyright (c) 2012 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/render_thread_impl.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+#include <string>
+
+class RenderThreadImplUnittest : public testing::Test {
+ public:
+  RenderThreadImplUnittest()
+      : kCustomizableHistogram_("Histogram1"),
+        kNormalHistogram_("Histogram2") {}
+  ~RenderThreadImplUnittest() {}
+ protected:
+  virtual void SetUp() OVERRIDE {
+    histogram_customizer_.custom_histograms_.clear();
+    histogram_customizer_.custom_histograms_.insert(kCustomizableHistogram_);
+  }
+  RenderThreadImpl::HistogramCustomizer histogram_customizer_;
+  const char* kCustomizableHistogram_;
+  const char* kNormalHistogram_;
+};
+
+TEST_F(RenderThreadImplUnittest, CustomHistogramsWithNoNavigations) {
+  // First there is no page -> no custom histograms.
+  EXPECT_EQ(kCustomizableHistogram_,
+            histogram_customizer_.ConvertToCustomHistogramName(
+                kCustomizableHistogram_));
+  EXPECT_EQ(kNormalHistogram_,
+            histogram_customizer_.ConvertToCustomHistogramName(
+                kNormalHistogram_));
+}
+
+TEST_F(RenderThreadImplUnittest, CustomHistogramsForOneRenderView) {
+  histogram_customizer_.RenderViewNavigatedToHost("mail.google.com", 1);
+  EXPECT_EQ(std::string(kCustomizableHistogram_) + ".gmail",
+            histogram_customizer_.ConvertToCustomHistogramName(
+                kCustomizableHistogram_));
+  EXPECT_EQ(kNormalHistogram_,
+            histogram_customizer_.ConvertToCustomHistogramName(
+                kNormalHistogram_));
+  histogram_customizer_.RenderViewNavigatedToHost("docs.google.com", 1);
+  EXPECT_EQ(std::string(kCustomizableHistogram_) + ".docs",
+            histogram_customizer_.ConvertToCustomHistogramName(
+                kCustomizableHistogram_));
+  histogram_customizer_.RenderViewNavigatedToHost("nottracked.com", 1);
+  EXPECT_EQ(kCustomizableHistogram_,
+            histogram_customizer_.ConvertToCustomHistogramName(
+                kCustomizableHistogram_));
+}
+
+TEST_F(RenderThreadImplUnittest, CustomHistogramsForTwoRenderViews) {
+  // First there is only one view.
+  histogram_customizer_.RenderViewNavigatedToHost("mail.google.com", 1);
+  // Second view created and it navigates to the same host -> we can have a
+  // custom diagram.
+  histogram_customizer_.RenderViewNavigatedToHost("mail.google.com", 2);
+  EXPECT_EQ(std::string(kCustomizableHistogram_) + ".gmail",
+            histogram_customizer_.ConvertToCustomHistogramName(
+                kCustomizableHistogram_));
+  EXPECT_EQ(kNormalHistogram_,
+            histogram_customizer_.ConvertToCustomHistogramName(
+                kNormalHistogram_));
+  // Now the views diverge (one of them navigates to a different host) -> no
+  // custom diagram.
+  histogram_customizer_.RenderViewNavigatedToHost("docs.google.com", 2);
+  EXPECT_EQ(kCustomizableHistogram_,
+            histogram_customizer_.ConvertToCustomHistogramName(
+                kCustomizableHistogram_));
+  // After this point, there will never be a custom diagram again, even if the
+  // view navigated back to the common host.

[Charlie Reis, 2012/08/23 16:30:40]

Are you ok with there being a custom histogram again if the second view is
closed and the first view navigates?  I think that will be considered a common
host again.

[marja, 2012/08/24 09:29:10]

I think so; I'd assume that all resources from the second view, from V8 point of
view, should be cleaned at that point. jochen, can you confirm this? (Another
possibility would be to do the custom histograms only if there is only one
render view, we'd probably get enough data from that, too...)

+  histogram_customizer_.RenderViewNavigatedToHost("mail.google.com", 2);
+  EXPECT_EQ(kCustomizableHistogram_,
+            histogram_customizer_.ConvertToCustomHistogramName(
+                kCustomizableHistogram_));
+}