Added UMA collection for fullscreen / mouse lock bubble re-shows.

chrome/browser/ui/exclusive_access/fullscreen_controller_state_unittest.cc

Index: chrome/browser/ui/exclusive_access/fullscreen_controller_state_unittest.cc
diff --git a/chrome/browser/ui/exclusive_access/fullscreen_controller_state_unittest.cc b/chrome/browser/ui/exclusive_access/fullscreen_controller_state_unittest.cc
index 9bd0d34ede37a9019e858f2abdc4fbb30c5a845a..f1129e585528d9bf55d4aaa82afa4f88b2aa306a 100644
--- a/chrome/browser/ui/exclusive_access/fullscreen_controller_state_unittest.cc
+++ b/chrome/browser/ui/exclusive_access/fullscreen_controller_state_unittest.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "base/command_line.h"
+#include "base/test/histogram_tester.h"
 #include "build/build_config.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_tabstrip.h"
@@ -20,6 +21,10 @@
 // the FullscreenController through all permutations of events. The behavior
 // of the BrowserWindow is mocked via FullscreenControllerTestWindow.
 
+namespace {
+
+const char kFullscreenReshowHistogramName[] =
+    "ExclusiveAccess.FullscreenBubbleReshowsPerSession";
 
 // FullscreenControllerTestWindow ----------------------------------------------
 
@@ -246,6 +251,8 @@ void FullscreenControllerTestWindow::UpdateExclusiveAccessExitBubbleContent(
 
 void FullscreenControllerTestWindow::OnExclusiveAccessUserInput() {}
 
+}  // namespace
+
 // FullscreenControllerStateUnitTest -------------------------------------------
 
 // Unit test fixture testing Fullscreen Controller through its states. Most of
@@ -474,15 +481,22 @@ TEST_F(FullscreenControllerStateUnitTest,
 
 // Test that switching tabs takes the browser out of tab fullscreen.
 TEST_F(FullscreenControllerStateUnitTest, ExitTabFullscreenViaSwitchingTab) {
+  base::HistogramTester histogram_tester;
+
   AddTab(browser(), GURL(url::kAboutBlankURL));
   AddTab(browser(), GURL(url::kAboutBlankURL));
   ASSERT_TRUE(InvokeEvent(TAB_FULLSCREEN_TRUE));
   ASSERT_TRUE(InvokeEvent(WINDOW_CHANGE));
   ASSERT_TRUE(browser()->window()->IsFullscreen());
+  histogram_tester.ExpectTotalCount(kFullscreenReshowHistogramName, 0);
 
   browser()->tab_strip_model()->SelectNextTab();
   ChangeWindowFullscreenState();
   EXPECT_FALSE(browser()->window()->IsFullscreen());
+
+  // Do a simple test that histograms are being recorded upon exiting the
+  // fullscreen session.
+  histogram_tester.ExpectUniqueSample(kFullscreenReshowHistogramName, 0, 1);

[dominickn, 2016/02/23 00:05:27]

Nit: is there a test that reshows the bubble so you can check samples go into
the histogram? Or can you add a test that manually triggers the bubble?

[Matt Giuca, 2016/02/23 02:50:28]

No, there isn't. I tried writing some minimal tests yesterday but I think we
just need to start a brand new unit test from scratch.

These "unit tests" are extremely heavyweight and involve spinning up a browser
window. I would have to simulate mouse movements, timers, etc. I don't really
want to add more of these. I just want a simple unit test around
FullscreenController, but there isn't one.

At least for now this shows that we record to the histogram. I plan to add
comprehensive unit tests for the exclusive access classes in the future, and
this will be included there.

[dominickn, 2016/02/23 03:05:53]

Acknowledged.

 }
 
 // Test that switching tabs via detaching the active tab (which is in tab