Add SiteIsolation.IsolateExtensions metrics and tests.

chrome/browser/site_details_browsertest.cc

Index: chrome/browser/site_details_browsertest.cc
diff --git a/chrome/browser/site_details_browsertest.cc b/chrome/browser/site_details_browsertest.cc
index b84be4c35683083c48fd03b4448c0c2d97fc105d..f6671c9e4ad1cd6d4b7868868d72bf0153653cfb 100644
--- a/chrome/browser/site_details_browsertest.cc
+++ b/chrome/browser/site_details_browsertest.cc
@@ -5,22 +5,33 @@
 #include "chrome/browser/site_details.h"
 
 #include "base/bind_helpers.h"
+#include "base/files/file_path.h"
 #include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
 #include "base/test/histogram_tester.h"
+#include "chrome/browser/extensions/extension_browsertest.h"
+#include "chrome/browser/extensions/test_extension_dir.h"
 #include "chrome/browser/metrics/metrics_memory_details.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
+#include "chrome/common/url_constants.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/test/browser_test_utils.h"
 #include "content/public/test/test_utils.h"
+#include "extensions/common/value_builder.h"
 #include "net/dns/mock_host_resolver.h"
 #include "net/test/embedded_test_server/embedded_test_server.h"
 #include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
 
 using base::Bucket;
+using content::WebContents;
+using extensions::DictionaryBuilder;
+using extensions::Extension;
+using extensions::ListBuilder;
+using extensions::TestExtensionDir;
 using testing::ContainerEq;
 using testing::ElementsAre;
 
@@ -57,7 +68,7 @@ class TestMemoryDetails : public MetricsMemoryDetails {
 
 }  // namespace
 
-class SiteDetailsBrowserTest : public InProcessBrowserTest {
+class SiteDetailsBrowserTest : public ExtensionBrowserTest {
  public:
   SiteDetailsBrowserTest() {}
   ~SiteDetailsBrowserTest() override {}
@@ -73,14 +84,55 @@ class SiteDetailsBrowserTest : public InProcessBrowserTest {
     ASSERT_TRUE(embedded_test_server()->InitializeAndWaitUntilReady());
   }
 
+  // Create and install an extension that has a couple of web-accessible
+  // resources and, optionally, a background process.
+  const Extension* CreateExtension(const std::string& name,

[nasko, 2015/09/04 22:19:43]

Why create extension by writing it to the filesystem instead of loading one from
chrome/test directory?

[ncarter (slow), 2015/09/10 19:08:59]

First off: I'm using an established practice -- dynamic extensions like this are
not uncommon, and classes like TestExtensionDir and DictionaryBuilder exist
precisely to support that pattern.

It's kind of a long story how I got here, but since you asked: Originally I
wanted to use existing extensions, but all the existing ones that had iframes
were in the "apitest" test data directory, and referencing them from a
non-apitest seemed like it would be a kind of layering violation, in that people
editing the original apitests might be surprised to see random distant tests
depending on their test data.

Then, Devlin pointed me at
chrome/browser/extensions/active_script_controller_browsertest.cc as a model to
follow, and that used this model, so I built on top of it. It proved to be a
good idea, because doing it this way turned out to have two practical benefits I
didn't anticipate:

1. We are able to embed the iframe url in http_iframe.html directly in the
extension content (line 113 below) -- which was fortuitous, because it turns out
that you can't do ExecuteJavascript from an extension iframe by default, unless
you relax the CSP in the manifest (
https://developer.chrome.com/extensions/contentSecurityPolicy ).  And because
ExecuteJavascript doesn't work, NavigateIframeToURL doesn't work either, so it
winds up being pretty tough to point extension content at the testserver port,
so that you can get web content. So I could have made it work with a static
extension, but there would have been many extra hoops there -- I probably would
have had to use postMessage to deliver the URL, and manually mess around with
test navigation observers.

2. Another thing that would have required extra work is the fact that I needed
to load three extensions. Since extension1 and extension2 have different
behavior that probably would have required 2 manifests and 2 extension
directories -- fine. But I also, I think, would have had to create a copy for
extension3, since just loading extension2 the second time would generate the
same extension id (the ID of an unpacked extension is determined by the path of
the directory, per https://developer.chrome.com/extensions/overview ). When I'm
creating the directory dynamically, I get fresh IDs even when reloading, making
it trivial to add "extension4" if I needed it.

I'm also fond of this approach because it makes it easier to see at a glance the
differences between extension1 and extension2, and why they're different. You
can't add comments to an on-disk manifest file to clarify that. Here it ought to
be pretty clear that has_background_process controls the differences between the
behaviors.

[nasko, 2015/09/11 18:14:11]

Thanks for the detailed answer!

+                                   bool has_background_process) {
+    scoped_ptr<TestExtensionDir> dir(new TestExtensionDir);
+
+    DictionaryBuilder manifest;
+    manifest.Set("name", name)
+        .Set("version", "1.0")
+        .Set("manifest_version", 2)
+        .Set("web_accessible_resources", ListBuilder()
+                                             .Append("blank_iframe.html")
+                                             .Append("http_iframe.html"));
+
+    if (has_background_process) {
+      manifest.Set("background",
+                   DictionaryBuilder().Set("scripts",
+                                           ListBuilder().Append("script.js")));
+      dir->WriteFile(FILE_PATH_LITERAL("script.js"),
+                     "console.log('" + name + " running');");
+    }
+
+    dir->WriteFile(FILE_PATH_LITERAL("blank_iframe.html"),
+                   "<html><body>" + name +
+                       ", blank iframe: "
+                       "<iframe width=40 height=40></iframe></body></html>");
+    GURL iframe_url = embedded_test_server()->GetURL("w.com", "/title1.html");
+    dir->WriteFile(FILE_PATH_LITERAL("http_iframe.html"),
+                   "<html><body>" + name +
+                       ", http:// iframe: "
+                       "<iframe width=40 height=40 src='" +
+                       iframe_url.spec() + "'></iframe></body></html>");
+    dir->WriteManifest(manifest.ToJSON());
+
+    const Extension* extension = LoadExtension(dir->unpacked_path());
+    EXPECT_TRUE(extension);
+    temp_dirs_.push_back(dir.release());
+    return extension;
+  }
+
  private:
+  ScopedVector<TestExtensionDir> temp_dirs_;
   DISALLOW_COPY_AND_ASSIGN(SiteDetailsBrowserTest);
 };
 
 // Test the accuracy of SiteDetails process estimation, in the presence of
 // multiple iframes, navigation, multiple BrowsingInstances, and multiple tabs
 // in the same BrowsingInstance.
-IN_PROC_BROWSER_TEST_F(SiteDetailsBrowserTest, ManyCrossSiteIframes) {
+IN_PROC_BROWSER_TEST_F(SiteDetailsBrowserTest, ManyIframes) {
   // Page with 14 nested oopifs across 9 sites (a.com through i.com).
   // None of these are https.
   GURL abcdefghi_url = embedded_test_server()->GetURL(
@@ -116,6 +168,15 @@ IN_PROC_BROWSER_TEST_F(SiteDetailsBrowserTest, ManyCrossSiteIframes) {
   EXPECT_THAT(details->uma()->GetAllSamples(
                   "SiteIsolation.IsolateHttpsSitesProcessCountNoLimit"),
               ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(1, 1)));
 
   // Navigate to a different, disjoint set of 7 sites.
   GURL pqrstuv_url = embedded_test_server()->GetURL(
@@ -150,6 +211,15 @@ IN_PROC_BROWSER_TEST_F(SiteDetailsBrowserTest, ManyCrossSiteIframes) {
   EXPECT_THAT(details->uma()->GetAllSamples(
                   "SiteIsolation.IsolateHttpsSitesProcessCountNoLimit"),
               ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(1, 1)));
 
   // Open a second tab (different BrowsingInstance) with 4 sites (a through d).
   GURL abcd_url = embedded_test_server()->GetURL(
@@ -183,6 +253,15 @@ IN_PROC_BROWSER_TEST_F(SiteDetailsBrowserTest, ManyCrossSiteIframes) {
   EXPECT_THAT(details->uma()->GetAllSamples(
                   "SiteIsolation.IsolateHttpsSitesProcessCountNoLimit"),
               ElementsAre(Bucket(2, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(2, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(2, 1)));
 
   // Open a third tab (different BrowsingInstance) with the same 4 sites.
   AddTabAtIndex(2, abcd_url, ui::PAGE_TRANSITION_TYPED);
@@ -215,11 +294,20 @@ IN_PROC_BROWSER_TEST_F(SiteDetailsBrowserTest, ManyCrossSiteIframes) {
   EXPECT_THAT(details->uma()->GetAllSamples(
                   "SiteIsolation.IsolateHttpsSitesProcessCountNoLimit"),
               ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(3, 1)));
 
-  // Do a window.open() to obtain a fourth tab in the same BrowsingInstance as
-  // the third tab. The new page uses the same four sites "a-d" as third tab,
+  // From the third tab, window.open() a fourth tab in the same
+  // BrowsingInstance, to a page using the same four sites "a-d" as third tab,
   // plus an additional site "e". The estimated process counts should increase
-  // by one (not five) from the previous result, since the new tab can reuse the
+  // by one (not five) from the previous scenario, as the new tab can reuse the
   // four processes already in the BrowsingInstance.
   GURL dcbae_url = embedded_test_server()->GetURL(
       "a.com", "/cross_site_iframe_factory.html?d(c(b(a(e))))");
@@ -260,4 +348,228 @@ IN_PROC_BROWSER_TEST_F(SiteDetailsBrowserTest, ManyCrossSiteIframes) {
   EXPECT_THAT(details->uma()->GetAllSamples(
                   "SiteIsolation.IsolateHttpsSitesProcessCountNoLimit"),
               ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(3, 1)));
+}
+
+IN_PROC_BROWSER_TEST_F(SiteDetailsBrowserTest, IsolateExtensions) {
+  // We start on "about:blank", which should be credited with a process in this
+  // case.
+  scoped_refptr<TestMemoryDetails> details = new TestMemoryDetails();
+  details->StartFetchAndWait();
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.CurrentRendererProcessCount"),
+              ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(1, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(1, 1)));
+
+  // Install one script-injecting extension with background page, and an
+  // extension with web accessible resources.
+  const Extension* extension1 = CreateExtension("Extension One", true);
+  const Extension* extension2 = CreateExtension("Extension Two", false);
+
+  // Open two a.com tabs (with cross site http iframes). IsolateExtensions mode
+  // should have no effect so far, since there are no frames straddling the
+  // extension/web boundary.
+  GURL tab1_url = embedded_test_server()->GetURL(
+      "a.com", "/cross_site_iframe_factory.html?a(b,c)");
+  ui_test_utils::NavigateToURL(browser(), tab1_url);
+  WebContents* tab1 = browser()->tab_strip_model()->GetWebContentsAt(0);
+  GURL tab2_url = embedded_test_server()->GetURL(
+      "a.com", "/cross_site_iframe_factory.html?a(d,e)");
+  AddTabAtIndex(1, tab2_url, ui::PAGE_TRANSITION_TYPED);
+  WebContents* tab2 = browser()->tab_strip_model()->GetWebContentsAt(1);
+
+  details = new TestMemoryDetails();
+  details->StartFetchAndWait();
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.CurrentRendererProcessCount"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(2, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(3, 1)));
+
+  // Test that "one process per extension" applies even when web content has an
+  // extension iframe.
+
+  // Tab1 navigates its first iframe to a resource of extension1. This shouldn't
+  // result in a new extension process (it should share with extension1's
+  // background page).
+  content::NavigateIframeToURL(
+      tab1, "child-0", extension1->GetResourceURL("/blank_iframe.html"));
+  details = new TestMemoryDetails();
+  details->StartFetchAndWait();
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.CurrentRendererProcessCount"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(2, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(3, 1)));
+
+  // Tab2 navigates its first iframe to a resource of extension1. This also
+  // shouldn't result in a new extension process (it should share with the
+  // background page and the other iframe).
+  content::NavigateIframeToURL(
+      tab2, "child-0", extension1->GetResourceURL("/blank_iframe.html"));
+  details = new TestMemoryDetails();
+  details->StartFetchAndWait();
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.CurrentRendererProcessCount"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(2, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(3, 1)));
+
+  // Tab1 navigates its second iframe to a resource of extension2. This SHOULD
+  // result in a new process since extension2 had no existing process.
+  content::NavigateIframeToURL(
+      tab1, "child-1", extension2->GetResourceURL("/blank_iframe.html"));
+  details = new TestMemoryDetails();
+  details->StartFetchAndWait();
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.CurrentRendererProcessCount"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(4, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(4, 1)));
+
+  // Tab2 navigates its second iframe to a resource of extension2. This should
+  // share the existing extension2 process.
+  content::NavigateIframeToURL(
+      tab2, "child-1", extension2->GetResourceURL("/blank_iframe.html"));
+  details = new TestMemoryDetails();
+  details->StartFetchAndWait();
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.CurrentRendererProcessCount"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(4, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(4, 1)));
+
+  // Install extension3 (identical config to extension2)
+  const Extension* extension3 = CreateExtension("Extension Three", false);
+
+  // Navigate Tab2 to a top-level page from extension3.

[nasko, 2015/09/04 22:19:43]

It is useful to state verbally what we expect to change and why, like you do in
the other cases so far.

[ncarter (slow), 2015/09/10 19:08:59]

Done.

+  ui_test_utils::NavigateToURL(browser(),
+                               extension3->GetResourceURL("blank_iframe.html"));
+  details = new TestMemoryDetails();
+  details->StartFetchAndWait();
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.CurrentRendererProcessCount"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(4, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(4, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(4, 1)));
+
+  // Add a web iframe to the chrome-extension:// page. This should create a new

[nasko, 2015/09/04 22:19:43]

You aren't really adding it to a page, rather navigating to an extensions page
with web iframe.

[ncarter (slow), 2015/09/10 19:08:59]

Done.

+  // process.
+  ui_test_utils::NavigateToURL(browser(),
+                               extension3->GetResourceURL("http_iframe.html"));
+  details = new TestMemoryDetails();
+  details->StartFetchAndWait();
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.CurrentRendererProcessCount"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(5, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(4, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(5, 1)));
+
+  // Navigate tab1 to the extension3 page. There should be 3 processes estimated
+  // by IsolateExtensions: one for extension3, one for extension1's background
+  // page, and one for the web iframe in tab2.
+  browser()->tab_strip_model()->ActivateTabAt(0, true);
+  ui_test_utils::NavigateToURL(browser(),
+                               extension3->GetResourceURL("blank_iframe.html"));
+  details = new TestMemoryDetails();
+  details->StartFetchAndWait();
+

[nasko, 2015/09/04 22:19:43]

No need for empty line, to stay consistent with code above.

[ncarter (slow), 2015/09/10 19:08:59]

Done.

+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.CurrentRendererProcessCount"),
+              ElementsAre(Bucket(2, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(3, 1)));
+
+  // Put a web iframe in tab1 as well. This could share a process with tab2's
+  // iframe (the LowerBound number), or it could get its own process (the
+  // Estimate number).
+  ui_test_utils::NavigateToURL(browser(),
+                               extension3->GetResourceURL("http_iframe.html"));
+  details = new TestMemoryDetails();
+  details->StartFetchAndWait();
+

[nasko, 2015/09/04 22:19:43]

No need for empty line, to stay consistent with code above.

[ncarter (slow), 2015/09/10 19:08:59]

Done.

+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.CurrentRendererProcessCount"),
+              ElementsAre(Bucket(2, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountEstimate"),
+              ElementsAre(Bucket(4, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountLowerBound"),
+              ElementsAre(Bucket(3, 1)));
+  EXPECT_THAT(details->uma()->GetAllSamples(
+                  "SiteIsolation.IsolateExtensionsProcessCountNoLimit"),
+              ElementsAre(Bucket(4, 1)));
 }