[BrowserSwitcher] Add ${edge} preset browser

On Windows, the AlternativeBrowserPath policy can now be set to
"${edge}", to open Microsoft Edge instead of IE.

This will display the browser name as "Microsoft Edge" on the
interstitial before opening it:

https://i.imgur.com/Qr1rPs4.png

Bug: 1124758
Change-Id: Ibe3c24b209c1054510cceb4b0237cf068acb84ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2414621
Commit-Queue: Nicolas Ouellet-Payeur <nicolaso@chromium.org>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807979}

chrome/browser/browser_switcher/alternative_browser_driver.h

@@ -21,7 +21,8 @@ namespace browser_switcher {
 
 class BrowserSwitcherPrefs;
 
-// Used for UMA metrics.
+// Used for UMA metrics, so do NOT change the order and the numbers. If you want
+// to add a new type, only append/increment.
 enum class BrowserType {
   kUnknown = 0,
   kIE = 1,
@@ -29,7 +30,8 @@ enum class BrowserType {
   kOpera = 3,
   kSafari = 4,
   kChrome = 5,
-  kMaxValue = kChrome,
+  kEdge = 6,
+  kMaxValue = kEdge,
 };
 
 // Interface for a helper class that does I/O operations for an

chrome/browser/browser_switcher/alternative_browser_driver_posix.cc

@@ -31,6 +31,9 @@ using LaunchCallback = AlternativeBrowserDriver::LaunchCallback;
 
 const char kUrlVarName[] = "${url}";
 
+// TODO(crbug.com/1124758): add ${edge} on macOS/Linux once it's released on
+// those platforms.
+
 #if defined(OS_MAC)
 const char kChromeExecutableName[] = "Google Chrome";
 const char kFirefoxExecutableName[] = "Firefox";

chrome/browser/browser_switcher/alternative_browser_driver_unittest.cc

@@ -119,6 +119,10 @@ TEST_F(AlternativeBrowserDriverTest, GetBrowserName) {
   SetBrowserPath("${ie}");
   actual = driver()->GetBrowserName();
   EXPECT_EQ("Internet Explorer", actual);
+
+  SetBrowserPath("${edge}");
+  actual = driver()->GetBrowserName();
+  EXPECT_EQ("Microsoft Edge", actual);
 #endif
 
 #if defined(OS_WIN) || defined(OS_MAC)
@@ -173,6 +177,10 @@ TEST_F(AlternativeBrowserDriverTest, GetBrowserType) {
       "C:\\Program Files (x86)\\Google\\Chrome\\Application\\chrome.exe");
   actual = driver()->GetBrowserType();
   EXPECT_EQ(BrowserType::kChrome, actual);
+
+  SetBrowserPath("${edge}");
+  actual = driver()->GetBrowserType();
+  EXPECT_EQ(BrowserType::kEdge, actual);
 #endif
 
 #if defined(OS_WIN) || defined(OS_MAC)

chrome/browser/browser_switcher/alternative_browser_driver_win.cc

@@ -44,6 +44,8 @@ const wchar_t kSafariKey[] =
     L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\App Paths\\safari.exe";
 const wchar_t kChromeKey[] =
     L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\App Paths\\chrome.exe";
+const wchar_t kEdgeKey[] =
+    L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\App Paths\\msedge.exe";
 
 const wchar_t kIExploreDdeHost[] = L"IExplore";
 
@@ -52,12 +54,14 @@ const wchar_t kIEVarName[] = L"${ie}";
 const wchar_t kFirefoxVarName[] = L"${firefox}";
 const wchar_t kOperaVarName[] = L"${opera}";
 const wchar_t kSafariVarName[] = L"${safari}";
+const wchar_t kEdgeVarName[] = L"${edge}";
 
 // Case-insensitive, typical filenames for popular browsers' executables.
 const wchar_t kChromeTypicalExecutable[] = L"chrome.exe";
 const wchar_t kIETypicalExecutable[] = L"iexplore.exe";
 const wchar_t kFirefoxTypicalExecutable[] = L"firefox.exe";
 const wchar_t kOperaTypicalExecutable[] = L"launcher.exe";
+const wchar_t kEdgeTypicalExecutable[] = L"msedge.exe";
 
 struct BrowserVarMapping {
   const wchar_t* var_name;
@@ -77,6 +81,8 @@ const BrowserVarMapping kBrowserVarMappings[] = {
     {kOperaVarName, kOperaKey, kOperaTypicalExecutable, "Opera",
      BrowserType::kOpera},
     {kSafariVarName, kSafariKey, L"", "Safari", BrowserType::kSafari},
+    {kEdgeVarName, kEdgeKey, kEdgeTypicalExecutable, "Microsoft Edge",
+     BrowserType::kEdge},
 };
 
 // DDE Callback function which is not used in our case at all.

tools/metrics/histograms/enums.xml

@@ -8598,6 +8598,7 @@ Called by update_bad_message_reasons.py.-->
   <int value="3" label="Opera"/>
   <int value="4" label="Safari"/>
   <int value="5" label="Chrome"/>
+  <int value="6" label="Edge"/>
 </enum>
 
 <enum name="BrowsingDataRemoverTasks">