Removes 'cause' from launchParams.

The explainer is being updated to indicate that websites should use
the presence of 'files' and 'request' to determine the cause of
launches.

Note: This API is hidden behind the NativeFileSystemAPI and
FileHandling blink flags.

Bug: 829689
Change-Id: Ia8a39ce36fee06281ab51e03c3ad2db401c105c4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1672611
Commit-Queue: Jay Harris <harrisjay@chromium.org>
Reviewed-by: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671988}

chrome/browser/ui/extensions/hosted_app_browsertest.cc

@@ -900,17 +900,9 @@ IN_PROC_BROWSER_TEST_P(HostedAppFileHandlingTest, PWAsCanViewLaunchParams) {
       OpenApplicationWindow(params, web_app_info.file_handler->action);
   navigation_observer.Wait();
 
-  base::Value expected(base::Value::Type::DICTIONARY);
-  expected.SetStringKey("cause", "default");
-  expected.SetIntKey("length", 0);
-
-  EXPECT_EQ(expected,
-            content::EvalJsWithManualReply(
+  EXPECT_EQ(0, content::EvalJs(
                    web_contents,
-                "getLaunchParams().then(params => {"
-                "domAutomationController.send({ cause: params.cause, length: "
-                "params.files.length });"
-                "});"));
+                   "getLaunchParams().then(params => params.files.length)"));
 }
 
 #if !defined(OS_ANDROID)

third_party/blink/renderer/modules/launch/dom_window_launch_params.cc

@@ -80,7 +80,7 @@ DOMWindowLaunchParams* DOMWindowLaunchParams::FromState(
     // params from the browser process, use that instead of hard coding the
     // launch params.
     supplement->launch_params_ = MakeGarbageCollected<LaunchParams>(
-        "default", HeapVector<Member<NativeFileSystemHandle>>());
+        HeapVector<Member<NativeFileSystemHandle>>());
   }
   return supplement;
 }

third_party/blink/renderer/modules/launch/launch_params.cc

@@ -9,9 +9,8 @@
 
 namespace blink {
 
-LaunchParams::LaunchParams(String cause,
-                           HeapVector<Member<NativeFileSystemHandle>> files)
-    : cause_(cause), files_(files) {}
+LaunchParams::LaunchParams(HeapVector<Member<NativeFileSystemHandle>> files)
+    : files_(files) {}
 
 LaunchParams::~LaunchParams() = default;
 

third_party/blink/renderer/modules/launch/launch_params.h

@@ -19,17 +19,15 @@ class LaunchParams final : public ScriptWrappable {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
-  LaunchParams(String cause, HeapVector<Member<NativeFileSystemHandle>> files);
+  LaunchParams(HeapVector<Member<NativeFileSystemHandle>> files);
   ~LaunchParams() override;
 
   // LaunchParams IDL interface.
-  const String& cause() { return cause_; }
   const HeapVector<Member<NativeFileSystemHandle>>& files() { return files_; }
 
   void Trace(blink::Visitor*) override;
 
  private:
-  String cause_;
   HeapVector<Member<NativeFileSystemHandle>> files_;
 };
 

third_party/blink/renderer/modules/launch/launch_params.idl

@@ -6,8 +6,6 @@
 // Explainer: https://github.com/WICG/file-handling/blob/master/explainer.md
 
 [RuntimeEnabled=FileHandling] interface LaunchParams {
-  readonly attribute DOMString cause;
-
   [SameObject]
   readonly attribute FrozenArray<FileSystemBaseHandle> files;
 };