Add a new field "source" in launchData of chrome.app.runtime.onLaunched() to trace launch source.

chrome/browser/ui/extensions/application_launch.cc

Index: chrome/browser/ui/extensions/application_launch.cc
diff --git a/chrome/browser/ui/extensions/application_launch.cc b/chrome/browser/ui/extensions/application_launch.cc
index 74ce425b27a4c7a6b53dae6f9dbbeb69348873bd..a09cac83c3672bcab22daf63035dce2258640b73 100644
--- a/chrome/browser/ui/extensions/application_launch.cc
+++ b/chrome/browser/ui/extensions/application_launch.cc
@@ -8,6 +8,7 @@
 
 #include "apps/launcher.h"
 #include "base/command_line.h"
+#include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/app_mode/app_mode_utils.h"
@@ -302,8 +303,13 @@ WebContents* OpenEnabledApplication(const AppLaunchParams& params) {
     PerAppSettingsServiceFactory::GetForBrowserContext(profile)->
         SetDesktopLastLaunchedFrom(extension->id(), params.desktop_type);
 
-    apps::LaunchPlatformAppWithCommandLine(
-        profile, extension, params.command_line, params.current_directory);
+    VLOG(2) << "Launch source: " << params.source;

[benwells, 2014/10/28 21:22:47]

Please remove before landing.

[cylee1, 2014/10/29 16:39:59]

Done.

+
+    apps::LaunchPlatformAppWithCommandLine(profile,
+                                           extension,
+                                           params.command_line,
+                                           params.current_directory,
+                                           params.source);
     return NULL;
   }
 
@@ -344,7 +350,9 @@ AppLaunchParams::AppLaunchParams(Profile* profile,
       desktop_type(chrome::GetActiveDesktop()),
       override_url(),
       override_bounds(),
-      command_line(CommandLine::NO_PROGRAM) {}
+      command_line(CommandLine::NO_PROGRAM),
+      source(extensions::SOURCE_UNKNOWN) {

[benwells, 2014/10/28 21:22:47]

Do you have any idea how many instances of launching this will cause to be
unknown? That is, did you try making this a required parameter to the Params
constructor and see how many call sites you'd have to update?

[cylee1, 2014/10/29 16:39:59]

I've checked all calls to OpenApplication
(https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/ui/...)
before start implementing. There're 36 occurrences in total for now (including
from test).

To be honest  I think it's more practical to make "source' an optional
parameters - starts from big entries and add minor entries in an on-demand
manner. For one, there are app-specific sources (e.g., calls from
wallpaper_manager_util.cc and first_run.cc, where only wallpaper app and first
run app will ever care about the source.) For the other, the calls to to
OpenApplication is likely to grow in the future so hard to keep track of every
entry points.

[benwells, 2014/10/30 06:04:28]

I am OK with starting like this, but I think you've missed some important call
sites. Before releasing this I'd like this parameter to be mandatory. It might
mean changing UNKNOWN to UNTRACED or something.

[cylee1, 2014/10/30 13:03:43]

In my proposal document I've listed a bunch of sources I can identify from
sources:
https://docs.google.com/a/chromium.org/document/d/1ozJ7ojy9bblBzivtBaGcNjTJJk...
So far I've implemented those "first tier" ones. Since I'm not very familiar
with the whole chrome apps code base, could tell me if you remember which
important sources I'm missing? 
If possible, I'd like to only include those most important sources in this CL,
and make up other sources in following CLs. Since this CL is getting larger I
feel it's getting hard to manage all changes in one CL. This feature is
protected by a flag so it should be safe.
Changed UNKNOWN to UNTRACKED

[cylee1, 2014/10/31 06:37:53]

I got what you mean, but I think it's fine to change UNKNOWN to UNTRACKED now if
I need to do it sooner or later.
Plus I also considered to use untracked instead of unknown earlier.

+}
 
 AppLaunchParams::AppLaunchParams(Profile* profile,
                                  const extensions::Extension* extension,
@@ -356,7 +364,8 @@ AppLaunchParams::AppLaunchParams(Profile* profile,
       desktop_type(chrome::GetActiveDesktop()),
       override_url(),
       override_bounds(),
-      command_line(CommandLine::NO_PROGRAM) {
+      command_line(CommandLine::NO_PROGRAM),
+      source(extensions::SOURCE_UNKNOWN) {
   // Look up the app preference to find out the right launch container. Default
   // is to launch as a regular tab.
   container =
@@ -374,7 +383,8 @@ AppLaunchParams::AppLaunchParams(Profile* profile,
       desktop_type(desktop_type),
       override_url(),
       override_bounds(),
-      command_line(CommandLine::NO_PROGRAM) {
+      command_line(CommandLine::NO_PROGRAM),
+      source(extensions::SOURCE_UNKNOWN) {
   if (disposition == NEW_FOREGROUND_TAB || disposition == NEW_BACKGROUND_TAB) {
     container = extensions::LAUNCH_CONTAINER_TAB;
   } else if (disposition == NEW_WINDOW) {