* Make TestHttpsInsecure test reliably passing on Darwin.

TestHttpsInsecure test runs a profiling session and checks that the
results contain expected function name. On OSX prior to 10.11 El Capitan
the SIGPROF signal is delivered to the process rather than to the thread
which skews the results enough for the test to fail.

Relax the check when running on OSX and other operating systems known to
have issues with the profiling signal (the list is taken from
src/runtime/pprof/pprof_test.go in Go source).

Also add the multiple variants of OSX to the continuous testing.

Fixes #146 and #156.

* Document the motivation for the empty loop.

Without the check, pprof may try using a path like "/pprof" when no
home environment variable is defined.

Fixes #148.

Detailed list of changes:
* Since the list of actions is now long, move it into
  an action box that is displayed only when applicable.
* Display help messages when hovering over action buttons.
* Hitting return in the search box invokes "focus" action.
* Cleaned up stale css entries.

I have attached one of the resulting pages to see what things look like easily.  It is static, so won't allow navigation to other pages, but should be interactive enough.

[benchcpu.zip](https://github.com/google/pprof/files/1151238/benchcpu.zip)

* Allow -http to accept host:port

* Add serveWebInterface tests.

* Make sure serveWebInterface is serving on the URL.

* Avoid nil pointer dereference

* Simplify the -http flag test.

* Use the right capitalization for hostport.

* Fix the double escaping in regexps.

* Address review comments.

* Added an interactive web interface triggered by passing -http=port
on the command line.  The interface is available by visiting
localhost:port in a browser.

Requirements:
* Graphviz must be installed.
* Browser must support Javascript.
* Tested in recent stable versions of chrome and firefox.

Features:
* The entry point is a dot graph display (equivalent to "web" output).
* Nodes in the graph can be selected by clicking.
* A regular expression can also be typed in for selection.
* The current selection (either list of nodes or a regexp)
  can be focused, ignored, or hidden.
* Source code or disassembly of the current selection can be displayed.

* Remove unused function.

* Skip graph generation test if graphviz is not installed.

* Added -http port and the various modes of using pprof to the
usage message.

* Web interface now supports "show" option.

* Web interface automatically opens the browser pointed at
the page corresponding to command line arguments.

* Some tweaks for firefox.

* Handle review comments (better usage message, more testing).

* Handled review comments:

1. Capture and display errors like "Focus expression matched no samples".
2. Re-ordered buttons to match other interfaces.
3. Use UI.PrintErr to print error messages.

* Handle javascript code review comments (a bunch of cleanups).
Also added pprof binary to .gitignore.

* Added info on focus/ignore/show/hide to legend on graphs

* Made separate function for formatting filters in legend

* Added files to enable fuzz testing
* Added test for crashes found with fuzzing
* fixed divide-by-zero error in profile/legacy_java_profile.go found with fuzzing

Fixes #142.

Fixes #144

* When pruning unsimplified names, don't trim "(anonymous namespace)".

Fixes #139.

* Fix copy/paste. Add test.

* Check for braces with a RE. Add more complex test cases. And operator().

* Fix last-minute debug.

* Construct bracketRx more cleanly

* spelling

* Redundant nil check

* While we're removing things...

* Add support for terabyte and petabyte memory units.

This fixes #137 (but not #136, this will come separately once we decide
what we want to do if anything).

* Add a test.

* Update copyright year

* Create a fake mapping for profile.proto profiles

If a profile has mappings but no profiles, pprof may be unable to
symbolize it offline, as it uses the mappings to keep track of which
locations need symbolization.

This fixes #120.

Added the test, verified it fails on Mac with Go 1.7 before the fix, and
passes with the fix. The test is done by augmenting the existing test
for handling https+insecure:// schema in URLs. This is a bit vague but I
figured that this test needed an updated anyway since as we moved it
recently we stopped exercising the symbolization as part of the test
which was its original intention in fixing #94. Can split the tests if
things do look too ugly.

* Fix the test to include the failed regex matching error in the message.

There is an issue where decreasing nodefraction (which should produce
more nodes) ended up reducing the number of displayed nodes.  This is
because we have an upper limit on number of nodes to display and the
number of node-lets counts against that limit.  This can cause a problem
if a node with large number of node-lets shows up near the front of
the list of nodes (e.g., std::allocator_traits::allocate in a heapz
profile had 102 node-lets, which caused all subsequent nodes to be
dropped).

Fixed by limiting the count of charged node-lets per node to
maxNodelets (4), which is the maximum number of node-lets we
display per node.

* Align file names in weblist disassembly

The disassembly displayed by weblist attempts to align file:line
information after each instruction, but two things interfere with this
alignment: 1) the instruction text often has tabs in it, which defeats
the length-based alignment and generally interacts poorly with HTML
rendering and 2) the instruction text often has special HTML
characters like < and > in it, but we pad the string after escaping
it, so the length is again not representative of how it will display.
For example, the following shows what this looks like for disassembly
that contains < and >:

                   .          .   41c634: cmp    $0x200,%rdx                               mgcsweepbuf.go:130
                   .          .   41c63b: jae    41c64f <runtime.(*gcSweepBuf).pop+0x4f> mgcsweepbuf.go:130
                   .          .   41c63d: mov    (%rax,%rdx,8),%rcx                        mgcsweepbuf.go:130
                   .          .   41c64f: callq  424800 <runtime.panicindex>             mgcsweepbuf.go:130
                   .          .   41c654: ud2                                              mgcsweepbuf.go:130

Fix these problems by replacing tab characters with spaces and padding
the string before escaping it. After this, the file names are properly
aligned:

                   .          .   41c634: cmp    $0x200,%rdx                               mgcsweepbuf.go:130
                   .          .   41c63b: jae    41c64f <runtime.(*gcSweepBuf).pop+0x4f>   mgcsweepbuf.go:130
                   .          .   41c63d: mov    (%rax,%rdx,8),%rcx                        mgcsweepbuf.go:130
                   .          .   41c64f: callq  424800 <runtime.panicindex>               mgcsweepbuf.go:130
                   .          .   41c654: ud2                                              mgcsweepbuf.go:130

* Separate discontiguous assembly blocks

Currently, weblist's disassembled output for each line simply lists
all instructions that are marked with that line number. This leads to
confusing disassembly because a lot of things look like straight-line
control flow when they aren't. For example, index panics look like
they always happen:

   .          .   41c62c: test   %al,(%rax)
   .          .   41c62e: and    $0x1ff,%edx
   .          .   41c634: cmp    $0x200,%rdx
   .          .   41c63b: jae    41c64f <runtime.(*gcSweepBuf).pop+0x4f>
   .          .   41c63d: mov    (%rax,%rdx,8),%rcx
   .          .   41c64f: callq  424800 <runtime.panicindex>
   .          .   41c654: ud2

In reality, 41c64f is at the end of the function, but it looks like we
call it immediately after a successful index operation.

Fix this by adding a vertical ellipses to separate blocks of assembly
that have other instructions between them. With this change, the above
looks like:

   .          .   41c62c: test   %al,(%rax)
   .          .   41c62e: and    $0x1ff,%edx
   .          .   41c634: cmp    $0x200,%rdx
   .          .   41c63b: jae    41c64f <runtime.(*gcSweepBuf).pop+0x4f>
   .          .   41c63d: mov    (%rax,%rdx,8),%rcx
                       ⋮
   .          .   41c64f: callq  424800 <runtime.panicindex>
   .          .   41c654: ud2

Use a more regular mechanism to name sources during driver tests and
recognize the naming during fetching to avoid saving the test profiles
into $HOME/pprof.

Also move the https+insecure testing into fetch_test, to focus it on
fetching the profile.

This fixes #107

internal/report: change the format of tags command output

This fixes #112

* Measure coverage of tests using codecov.io.

* Add codecov badge to README.md

* Recurse into packages when testing with coverage.

* Push testing kind of commands down to test.sh

This change also includes:
 - Instead of printing and sorting based on the first value in the
 internal value slice, use the sample type user selected.
 - Use the unit and print numbers in human friendly version.
 - Add a flag '-update' to internal/driver/driver_test to update the
 golden files.

 TODO: apply to other tests that use other golden files.

Generalize GetBase for shared libraries to handle cases when both process
mapping offset and program header addresses are non-zero.

Based on process mapping information, a sample at a virtual address x maps to
a file offset fx = x - map_start + map_offset.

The program header for the segment with the .text section may have non-zero
mapping information. Thus, a file offset fx maps to a symbol address
sx = fx - ph_offset + ph_virt_addr.

Thus, sx = x - map_start + map_offset - ph_offset + ph_virt_addr, and the base
address for symbolization is map_start - map_offset + ph_offset - ph_virt_addr.

* Recognize (again) https+insecure scheme for symbolization POSTs.

This reverts the revert of #111 relaxing the test to make it pass as the
issue reported in #111 is caused by unrelated #120.

Added a test, verified the test failed before the fix.

This fixes #94.

* Fix the staticcheck failure.

* `git ls-files -- '*.go' | xargs gofmt -s -w`

* driver: unexport InternalOptions

This was an exported method that returned an internal type, so it's
unlikely that anyone depends on its presence.

* internal/binutils: remove newline in error string

golint reported: error strings should not be capitalized or end with
punctuation or a newline

* internal/driver: s/buildId/buildID/ per golint

* internal/elfexec: remove punctuation in error string

golint reported: error strings should not be capitalized or end with
punctuation or a newline

* internal/graph: correct comment

Found with golint.

* internal/graph: add method comment

golint reported: exported method Edge.WeightValue should have comment
or be unexported

* internal/report: remove newline in error string

golint reported: error strings should not be capitalized or end with
punctuation or a newline

* *: remove unused code

Found with honnef.co/go/tools/cmd/unused:

	internal/binutils/disasm_test.go:137:8: const objdump is unused (U1000)
	internal/driver/driver_test.go:353:6: type testProfile is unused (U1000)
	internal/graph/graph.go:838:6: func countEdges is unused (U1000)
	profile/proto.go:148:6: func encodeStringOpt is unused (U1000)

* *: simply code

Found with honnef.co/go/tools/cmd/gosimple:

	internal/driver/commands.go:471:24: should omit comparison to bool constant, can be simplified to !b (S1002)
	internal/driver/driver.go:163:5: should omit comparison to bool constant, can be simplified to !trim (S1002)
	internal/driver/driver.go:168:5: should omit comparison to bool constant, can be simplified to !focus (S1002)
	internal/driver/driver.go:172:5: should omit comparison to bool constant, can be simplified to !tagfocus (S1002)
	internal/driver/driver.go:176:5: should omit comparison to bool constant, can be simplified to !hide (S1002)
	internal/graph/dotgraph.go:213:34: should use make(map[string][]*Tag) instead (S1019)
	internal/report/report.go:1061:3: should replace loop with label = append(label, rpt.options.ProfileLabels...) (S1011)
	profile/proto.go:157:5: should omit comparison to bool constant, can be simplified to !x (S1002)

* *: correct mistakes

Found with honnef.co/go/tools/cmd/staticcheck:

	driver/driver.go:280:20: infinite recursive call (SA5007)
	internal/driver/driver_focus.go:54:11: this value of err is never used (SA4006)
	profile/proto.go:74:32: x | 0 always equals x (SA4016)

* Add linters to .travis.yml

Clarify that Go 1.7 or newer is required.

Go 1.6 currently fails the tests with build error

`profile/legacy_profile_test.go:309: t.Run undefined (type *testing.T has no field or method Run)`

Alternatively, we can fix it but I am not sure there is a strong reason
to support Go 1.6 or older.

Also add build status badge in the README.md file.

Use wildcard versions for Go in Travis config.

So that the latest patch version is tested.

A change to trigger a test Travis build

Enable continuous integration with Travis CI

Revert "Recognize https+insecure scheme for symbolization POSTs."

Recognize https+insecure scheme for symbolization POSTs.

Added a test, verified the test failed before the fix.

This fixes #94.

Remove filenames when showing function (default) granularity

Add .gitignore

Previously we were showing filenames together with function names
when generating reports at function granularity. This was an attempt
to provide more information to the user, but it clutters the output.
Also, in cases where a function is associated to multiple files
(eg template instantiations in C++), keeping the filename may prevent
us from combining nodes from the same function.

Will stop keeping filenames at the default function granularity, and will
remove the "functionnameonly" option which was previously providing this
functionality.

Common files to be ignored in source tree.

pprof: clean up temp files created during tests