Move ALL_BROWSER_TYPES constant to a FindAllBrowsers() function, so that it doesn't run unnecessari…

tools/telemetry/telemetry/core/browser_finder.py

Index: tools/telemetry/telemetry/core/browser_finder.py
diff --git a/tools/telemetry/telemetry/core/browser_finder.py b/tools/telemetry/telemetry/core/browser_finder.py
index 633fcce25a574ea6c319220d4fcae252428d27d3..9a1e5f18aa9cf43ecf8d969f3f73aca38259a1e0 100644
--- a/tools/telemetry/telemetry/core/browser_finder.py
+++ b/tools/telemetry/telemetry/core/browser_finder.py
@@ -22,9 +22,6 @@ BROWSER_FINDERS = [
   webdriver_desktop_browser_finder,
   ]
 
-ALL_BROWSER_TYPES = reduce(operator.add,
-                           [bf.ALL_BROWSER_TYPES for bf in BROWSER_FINDERS])
-
 
 class BrowserTypeRequiredException(Exception):
   pass
@@ -35,6 +32,12 @@ class BrowserFinderException(Exception):
 
 
 @decorators.Cache
+def FindAllBrowserTypes():
+  return reduce(operator.add,
+                [bf.FindAllBrowserTypes() for bf in BROWSER_FINDERS])
+
+
+@decorators.Cache
 def FindBrowser(options):
   """Finds the best PossibleBrowser object given a BrowserOptions object.
 
@@ -67,7 +70,7 @@ def FindBrowser(options):
   default_browsers = []
   for finder in BROWSER_FINDERS:
     if (options.browser_type and options.browser_type != 'any' and
-        options.browser_type not in finder.ALL_BROWSER_TYPES):
+        options.browser_type not in finder.FindAllBrowserTypes()):
       continue
     curr_browsers = finder.FindAllAvailableBrowsers(options)
     new_default_browser = finder.SelectDefaultBrowser(curr_browsers)
@@ -96,7 +99,7 @@ def FindBrowser(options):
         '\n'.join(sorted(set([b.browser_type for b in browsers]))))
 
   if options.browser_type == 'any':
-    types = ALL_BROWSER_TYPES
+    types = FindAllBrowserTypes()
     def CompareBrowsersOnTypePriority(x, y):
       x_idx = types.index(x.browser_type)
       y_idx = types.index(y.browser_type)